There's an unexplained absence at the heart of Istanbul. Three-and-a-half hours from London, you can be sitting in a rooftop bar sipping a long cool drink with a view of a skyline that is simply beyond anything anywhere else in Europe. Before you is the sixth-century dome of the Haghia Sophia; beyond are the minarets of the Blue Mosque, and in the distance the islands of the Sea of Marmara.

Yet step away from the old imperial city and you'd be forgiven for thinking you're the only tourist in town. Somehow Istanbul, the capital of two of the greatest empires the world has known, seems to have fallen off the map. In this city, where the accretion of history is visible on every street corner, where people still bathe in 16th-century baths and shop in the medieval covered bazaar, where churches have minarets tacked on the sides, and women wear headscarves or Prada or sometimes both, you'll see fewer visitors than on a day-trip to Longleat.

It is, in any case, a city with a hole in it: a great watery void, that must be crossed, and recrossed by bridge, or by boat; that can be glimpsed from restaurant terraces or hotel windows, or suddenly, surprisingly, when rounding the corner of a street.

But where are the tourists? In the past ten years, Istanbul has re-invented itself. Bars, clubs, boutique hotels have mushroomed from nowhere; vibrant, modern adjuncts to the domes of Constantinople and the relics of Byzantium. But then the city, clinging precariously to the edge of Europe, straddling the continental divide, is a geopolitical conundrum that has yet to be solved. Sit on your hotel roof terrace, take another sip of your drink, listen to the call to prayer echoing from a minaret compete against the sound of drum-and-bass coming from a bar, and you'll start to understand why.

It was geography that determined the location of the city of Byzantium, and religion that underpinned its importance as Constantinople, but its engine, its beating heart, is, and always has been, trade.

Step inside the Grand Bazaar and you'll come to understand how the Emperor Justinian funded the soaring dome of the Haghia Sophia. Wander its 66 streets and 4,500 shops and you'll realise Suleyman's magnificence stemmed not just from the construction of his mosques and palaces, but his ability to raise the necessary taxes from his merchants.

It is commerce that has made the city what it is today. And the Grand Bazaar, with its carpets, kilims, gold jewellery, Beckham T-shirts, rip-off handbags, leather jackets, painted plates, evil eyes and hundreds upon hundreds of hawkers, touts and smooth-tongued salesmen, is its secular cathedral. Shop, or don't-shop, but stand amazed in any case by a vast, domed, arcaded building that has been standing, in part, since 1461, skilfully adapting itself to cater for every passing fad of every passing age.

Set out from the Nuruosmaniye Gate, stopping to peer into the adjacent 18th-century mosque of the same name, built in a style that is the Islamic counterpart to European Baroque. Straight ahead is the Kalpakcilar Basi Caddesi, the bazaar's main drag, atmospherically lit by apertures in the roof and twinkling lights from the stalls and shops on either side. Come on a weekday morning to escape the worst of the crowds. Istanbulis flood in on Saturdays to look at the gold - 100 tonnes a year is sold here, mostly to locals - and, even at other times, you'll find Western tourists are outnumbered by shoppers from neighbouring countries, particularly the former Soviet Union. This won't stop salesmen from assailing you from every doorway, however; if you're determined not to buy, smile and don't look at the goods. Even for a second. They're trained to hunt out your hidden desires.

Around the corner on Feraceciler Sokak is Sark Kahvesi, a charming vaulted café decorated with old Istanbul photos and frequented by old Istanbul men. Inside, birds swoop around the skylights and games of tavla go on for ever. Drink tea while you watch the shoppers sweep past. Two minutes away, off Fesciler Caddesi - Fez Street - is another peaceful retreat: Havuzlu Lokanta, a cavernous restaurant that is widely held to be the best in the bazaar.

From here, you'll have to backtrack along Zenneciler Sokak to fight your way into the oldest part of the bazaar, the Ic Bedesten, a great stone lock-up built in the 15th century for the most precious wares; silver and antiques are still sold beneath its great vaulted brick roof.

Goods are still concentrated around specific areas: Bodrum Hani for leather; Aga Sokak for gold and silver; and Yaglikcilar Sokak for fabrics. But, arguably, the best of the bazaar is located in the streets outside. Wander downhill through the back alleys towards the Golden Horn and explore the numerous hidden hans - medieval courtyards where you can still watch silver being cast or "Levi's" logos being stitched on to pairs of stonewashed jeans.

 Grand Bazaar, (Kapali Carsi), Beyazit. Open Mon-Sat 9am-7pm.

Beyoglu on foot
From the port in Karakoy take the Tunel, the oldest underground railway in Europe, up to Beyoglu. For centuries this was Istanbul's most cosmopolitan quartier, and remains its commercial heart today. Step into the tranquil courtyard of the Galata Mevlevihane, the oldest whirling dervish lodge in the city, to see the tombstones topped with the order's distinctive hats, before taking afternoon tea in the 19th-century surroundings of the Pera Palas Hotel (see Accommodation below). Ask at reception to see Room 101 - left untouched since Ataturk, founder of the modern state of Turkey, checked out.

 Galata Mevlevihane, Galip Dede Caddesi. Open 9.30am-4pm, closed Tuesday. 80p.

Tramride to the Golden Horn
When you've had all that you can take of the Grand Bazaar, buy a 40p token and hop on board a tram just outside the Beyazit Gate. It trundles its way past Haghia Sophia, the Blue Mosque, and then down to the Spice Bazaar and the Eminonu port. Here traders sell everything from pirated CDs to budgerigars, and hundreds of men and boys fish with rods over the side of the Galata Bridge. Follow the smell of frying fish to find the boats where the catch of the day is served up in sandwiches to a stream of hungry commuters.

The Bosphorus by boat
The only way to really get to grips with Istanbul's extraordinary topography is to take to the water. The most satisfying jaunt is a five-hour round-trip cruise along the shores of the Bosphorus, stopping at villages on both sides along the way. More simply, just turn up at any ferry pier in the city centre, catch a boat to Uskudar or Kadikoy and you'll find yourself in Asia.

 Ferries for the Bosphorus cruise leave year-round from pier 5, Eminonu. £3.

Sultanahmet by night
The silhouette of Haghia Sofia and the Blue Mosque is impressive by day, but unforgettable at night. Come at sunset to hear the call to prayer echoing across the rooftops, see the birds swooping among the minarets, and watch as the floodlights turn the domes eerie shades of green and pink. Afterwards head to the Four Seasons Hotel on Tevkifhane Sokak, just off the main square, for a drink on its rooftop bar and a view of the moon rising over the Sea of Marmara.

Topkapi Palace
For 400 years the Topkapi Palace was the hub of the Ottoman Empire. It served as the seat of government as well as being home to the Sultan and his several-thousand-strong retinue of guards, eunuchs, concubines and slaves. Situated on a promontory above the confluence of the Golden Horn, the Bosphorus and the Sea of Marmara, it stands aloof from the rest of the city, and still today offers a respite from the heaving streets below. Come here not just to glimpse the splendour of the Ottoman imperial court, but to take sanctuary in its peaceful, shady gardens and admire views that extend across Istanbul in all directions.

The palace is not a single building but a series of graceful interconnecting courtyards. As you proceed through the complex you move from more public sections, such as the Divan in the second court where the imperial councillors sat in session, to the private pavilions of the Sultan in the fourth and final courtyard.

The highlight of the palace is, theoretically, the harem or private quarters where the sultan's mother ruled over nearly a thousand slave girls, who would be groomed to become the Sultan's concubines. It's a warren of more than 300 rooms including luxurious hamams and exquisitely decorated chambers. But come early, or don't come at all. It's only possible to visit it on a guided tour, and when the number of visitors mounts up you'll find yourself in a mob, shunted around just a very small number of the rooms at break-neck speed.

Go instead to the imperial kitchens in the second courtyard, to be dazzled by the display of hundreds of priceless Chinese and Japanese porcelain platters - only a small selection of the 10,700 pieces that have survived to this day. Or visit the beautifully tiled Pavilion of the Sacred Relics in the third courtyard, home to some of Islam's holiest relics. These include one of the Prophet's teeth, fragments of his beard and, most precious of all, his Holy Mantle, which is kept in a gold coffer placed on a silver throne behind glass walls.

More relaxing than any of these, however, is the fourth and final courtyard. Here you can lounge pasha-like amid its pavilions, outdoor pools, shaded colonnades and scented rose garden and take in one of the best views of the city. Stop for a snack at the Konyali cafe and restaurant. The food isn't quite as inspiring as the setting, but the view from the terrace towards the Bosphorus and the Asian shore on the far side is undeniably magnificent.

Topkapi Palace, Sogukcesme Sokak,  Open 9am-5pm, closed Tues. Main complex £5, further £4 each for the harem and treasury.

Haghia Sophia
Nowhere is Istanbul's exceptional status as former capital of both the Christian and Islamic empires more evident than in this monumental basilica crowned with four minarets. Built by the Emperor Justinian in the sixth century, it was converted to a mosque by the conquering Ottoman armies in 1453. But it's only when you enter the building - now a museum - that you get a true sense of its awesome proportions. For a thousand years its dome was the largest in the world - 98 ft in diameter, surpassed only in the 16th century with the construction of St Peter's in Rome. Sit beneath the trees in the quiet courtyard café just outside the exit for a view of its extraordinary higgledy-piggledy exterior.

Sultanahmet Square . Open 9am-4.30pm, closed Mon,

Yerebatan Cistern
Built in the Byzantine period to store fresh water, the Yerebatan Cistern resembles not so much an underground reservoir as a vast subterranean temple. A strange coppery light reflects off the water and illuminates its columns - 336 of them in all - while fish swim just inches from your feet. It was rediscovered in the 16th century by a Frenchman who heard that local inhabitants drew water and even fish from their cellars. A raised gangway takes you on a circular tour to the far end, where two stunning Medusa heads serve as column bases, and back to the exit where an atmospheric waterside café serves drinks and snacks.

Yerebatan Caddesi 13  Open 9am-5.30pm.

The Blue Mosque
With its six minarets instead of the more usual four, Sultanahmet Mosque, to use its official name, is perhaps the most instantly recognisable - and unforgettable - silhouette on Istanbul's skyline. Directly facing Haghia Sofia, it was commissioned by Sultan Ahmet I in the early 1600s to rival the grand old lady of Christianity. Peek inside to see the wall-to-wall Iznik tiles, glazed predominantly in shades of blue, that have given the mosque its popular name. The large walled garden of Yesil Ev hotel on nearby Kabasakal Caddesi makes a restful spot for refreshments.

Sultanahmet Square . Open 9am-5pm. Free.

Archaeological Museum
Istanbul's archaeological museum is often overlooked by visitors - unjustly so. Its collection of antiquities reflects both the size and extent of the Ottoman Empire, and rivals that of the British Museum. The most spectacular of the exhibits, housed in the main neoclassical building, is the collection of sarcophagi, some with exquisitely intricate friezes, excavated from a royal necropolis at Sidon (in Lebanon).

 Entrance off the first courtyard of the Topkapi Palace . Open 9.30am-4pm, closed Mon. £2.

Turkish cuisine is among the best in the Mediterranean, drawing on a range of traditions - from elaborate meat stews created in the Sultans' palaces to simple peasant fare based on staples such as aubergines, tomatoes and beans. Our selection focuses on Turkish restaurants in areas you are likely to be staying in or to visit as a tourist - namely Sultanahmet, Beyoglu and Ortakoy (a 20-minute, £5-£7 taxi ride from Sultanahmet, or a 10-minute, £2 ride from Beyoglu).

Five top tables
Unless indicated otherwise, prices are for a three-course meal, excluding drinks.

Gourmand
Occupying part of a 19th-century Ottoman palace on the edge of the Bosphorus, Feriye combines an unbeatable location with an enticing menu that draws on old Ottoman recipes. Until late autumn, tables are set right by the water's edge where you can enjoy views of the soaring heights of the Bosphorus suspension bridge and beneath it the Ortakoy mosque. In winter the seating moves inside to an elegant room with a grand piano and floor-length windows overlooking the water. Food is essentially traditional Turkish with a modern twist. Starters, for example, include the usual mixed meze as well as more elaborate dishes such as manti (Turkish ravioli) with marinated seabass. Advance bookings advised.

 Kabatas Kultur Merkezi, Ciragan Caddesi 124   Open noon-3pm and 7pm-11pm. £20.

Nostalgic
Located in an Ottoman house overlooking both the Haghia Sofia and Blue Mosque, Rami offers typical Turkish dishes such as mixed dolma (stuffed peppers, courgettes and vine leaves) and karniyarik (an aubergine and minced lamb bake) in old-fashioned surroundings. The decor belongs to a more genteel era - tables are laid with starched white linen and silver trays serve as place mats. As in other restaurants in the area, the clientele is made up mainly of tourists, but Rami is one of Sultanahmet's more serene venues. Ring in advance to book a table with a view.

Utangac Sokak 6 . Open noon-11.30pm. £16.

Al fresco
Although many locals lament the transformation of the fishing hamlet of Ortakoy into a popular nightspot with many restaurants, bars and street stalls, it is still lovely, with the laid-back atmosphere of a seaside resort. Cinaralti, one of a string of waterfront restaurants with tables spilling into the harbour square, offers a wide range of meze followed by the catch of the day or grilled meats. You could happily spend a long evening here, dipping bread into platters of puréed aubergine and watching the street vendors peddling fresh nuts, luminous yo-yos and robotic dolls.

 Cinaralti Cafe and Restaurant, Iskele Meydani 44-46, Ortakoy . Open noon-2pm. £10.

Inexpensive
For good-value food in lively surroundings, it's hard to beat Nevizade Sokak in Beyoglu - a steep pedestrian street lined with small restaurants catering to couples on dates and large groups of friends. Street vendors and gypsy musicians add to the jollity. On any given evening it's guaranteed to be busy, though this won't stop each and every restaurant from touting for your business. Meze are the mainstay of a meal here and of the dozen or so possible venues, Imroz Lokantasi has a particularly good selection. As well as the more usual vegetable and fish dishes, you'll find delicacies such as a platter of brains.

Imroz Lokantasi, Nevizade Sokak 24 . Open noon-12am. £7.

On the hoof
Turkish snack food is among the best in the world. The most ubiquitous quick bites are: pide or Turkish pizza (kiymali - spicy minced lamb, tomato and onions - is the traditional topping); durum or kebab sandwiches, served in very fine pitta bread; and flat, savoury pancakes called gozleme. You'll find snack bars on every corner but for reliably good pide in the town centre, head to Beyoglu Konak 2, at the lower end of Istiklal Caddesi in Beyoglu. It's clean and bright with big glass chandeliers, red velvet furnishings and a view of Tunel Square from the upstairs salon. Kebabs and salads are also served. From here, it's a short hop to Tunel Gecidi, a pedestrian passage opposite the funicular station on Tunel Square. This narrow street is one of the prettiest in Beyoglu, with stacks of potted plants on the pavements and a handful of cafes and antique shops. For a coffee or something more substantial in cosy surroundings, try KaVe - the Sunday brunch buffet is accompanied by piano music (11am-2pm).

 Beyoglu Konak 2, Tunel Meydani 519 . Open 7am-10pm. £1.50 for a pide. KaVe, Tunel Gecidi 10, Beyoglu  Open 8am-2am. £11 for Sunday brunch.

Istanbul does have an opera house and a couple of concert halls, but they showcase alien art forms with no local tradition. Far more intriguing - and strangely mesmerising - is to watch a performance by members of the Mevlevi sect, the "Whirling Dervishes", accompanied by the melancholic sounds of Sufi music. The Galata Mevlevihane (see Beyoglu on foot above) has a performance on the last Sunday of each month. Buy tickets from the museum kiosk on Galip Dede Caddesi.

The Festival of Sufi Music and Ritual  runs until October 30, and is hosting performances inside the 19th-century Sirkeci train station (Mon, Weds, Fri 8.30pm; £6.50). On October 10, there is also a free concert of sufi music at 7pm in Hocapasa Mosque, Sirkeci. Buy tickets for both from the Harem music shop on Divanyolu Caddesi, just behind the Sultanahmet tram stop.

The whirling dervish ceremony, or Sema, was never intended to be a performance art, however. The rhythmic motion is supposed to be a means by which men can come to experience the divine, a purely spiritual act, and there are still places in Istanbul where the ceremony is performed in a mosque wholly for religious purposes. Fatih Tekke, in the ultra-conservative quarter called Fatih, for example, has services at around 8pm every Monday. Women must dress modestly, and cameras are strictly forbidden. This is not a tourist attraction, and it would be sensible to join the group that leaves from Les Arts Turcs gallery, on Incili Cavus Sokak, close to the Yerebatan cistern, at around 7pm (the time varies with sunset). This is a foundation that was set up to raise awareness of Turkish culture; it charges £17 for transport and the services of a guide. (0212 520 77 43, www.lesartsturcs.com.)

Until November 16, the Istanbul Foundation for Culture and Arts is hosting the 8th International Istanbul Biennial, featuring 85 artists from 42 countries at some of the most atmospheric locations in the city (including the Yerebatan cistern and an Ottoman customs warehouse on the banks of the Bosphorus), with a programme of exhibitions, installations, video screenings, concerts and much more . Istanbul's Hotels Fairs Lists (0212 520 77 43 - 0212 511 75 56)

Perhaps the greatest way of experiencing Turkish culture, however, and certainly the most intensely pleasurable, is to be stripped bare, laid upon a marble slab and pummelled all over. Baths, or hamams, still play a key part in Istanbul's daily life, and every neighbourhood boasts its own. If it's your first visit, you may feel more comfortable at one of the baths in the city centre, used to dealing with tourists.

Cemberlitas Hamami, Vezirhani Caddesi 8 , just by the tram stop of the same name in the Grand Bazaar area, is one of the most spectacular, dating from 1584 and designed by the architect of the nearby Suleymaniye mosque, the great Sinan. There are separate sections for men and women and it's open daily from 6am to midnight. Entrance costs £6, or with a massage £10, including soap, shampoo, towel and locker.

Bars & clubs
Sultanahmet boasts several superb rooftop bars that are perfect for a sunset drink (the Four Seasons Hotel on Tevkifhane Sokak and the Hotel Sari Konak on Mimar Mehmet Aga, both just off the main square, have two of the best). After dinner, though, finish the evening in a traditional smoking garden. Café Mesale, on Arasta Carsisi 45, yards from the Blue Mosque, is a large carpet-covered courtyard where waiters will bring you your own nargile or waterpipe, heated with charcoal, and filled with fragrant tobacco. The clientele is surprisingly mixed - half Turks, half tourists, and even if you don't partake, there's live music every night. It's open 24 hours a day.

To mix with Istanbul's young sophisticates, you'll have to head to Beyoglu or one of the villages on the Bosphorus such as Ortakoy (see Eating out above). Babylon  on Seyhbender Sokak 3, near the Pera Palas, is the best live music venue in town, hosting jazz singers, world music gigs and club nights. It's only open when there's an event (usually Weds-Sat), so check first. Dulcinea, on Meselik Sokak off Istiklal Caddesi , draws a fashionable crowd to its multi-function café, lounge and arts space and hosts concerts, installations, DJs, and various special events. Closed Sunday.

Alternatively wander up Istiklal Caddesi and join the parade of people hopping from one bar to the next. (Try the Turku Café Bar on Imam Adnan Sokak, for traditional live fasil music, or, opposite, the rather more sedate Kaktus with yellow walls and dark wood interior, both open until 2am.) Around the junction where Nevizade Sokak (see Eating out) meets Balo Sokak, you'll find any number of late, loud bars, some with live music, both traditional and modern, and crowds spilling out on to the street.

Getting there
Flights with British Airways (0870 850 9850, cost from £168.60 return in October, ex-Heathrow. A taxi ride to Sultanahmet will cost £6-£10, depending upon the time of day.

Getting around
In the city itself, you'll find that all of Sultanahmet is walkable. Otherwise it's easy to hop on and off the single tramway through the area. Taxis are cheap and plentiful. All have meters, and although some drivers may try to enforce a fixed fare, simply point to the meter and say gunduz (guhn-dooz), meaning daytime, or gece (geh-jay), night-time, as appropriate. The word will flash up on the screen when the meter is set. The starting fare is 45p by day, 90p by night.

Accommodation
All prices are for a double room in October and include breakfast and tax.

Ciragan Palace
For sheer five-star pzazz, this lavish 19th-century Ottoman palace (and modern annex) situated on the shores of the Bosphorus is unbeatable: sitting by the infinity pool watching the sun setting over the Asian shore is not an experience you'll easily forget. The interior décor is over-chintzy and rooms without a view of the water aren't worth the money, but this is still Istanbul's most luxurious hotel, with all the marble, gilt, and liveried porter trimmings.

 Ciragan Palace Hotel Kempinski, Ciragan Caddesi 32, Besiktas , Ciragan Palace Hotel ). Double rooms with sea view cost £260; book in the UK through.

Four Seasons
The other contender for the title of Istanbul's best hotel is housed in a former prison, a stone's throw from Sultanahmet Square. Although from the outside the building retains an air of austerity, its light interior boasts high ceilings, arched windows, Ottoman-era antiques and understated, neutral soft furnishings. There's a tranquil courtyard garden, and a rooftop bar - probably the best place in the city to watch the sun set over the domes and minarets of the Haghia Sofia.

 Four Seasons Hotel Istanbul, Tevkifhane Sokak 1 , Four Seasons Hotel).

Pera Palas
Guidebooks tend to gloat over this hotel's history, and then dismiss it as too shabby to stay in. But it is also a truly great hotel. Built in 1892 to house the passengers of the Orient Express, it's been left virtually untouched ever since. There are marble columns in the lobby, a grand piano in the dining room, red velvet bath chairs in the patisserie, and a wrought-iron lift with a mirror, crimson interior and uniformed attendant. Rooms have brass bedsteads, threadbare rugs and Seventies appliances left over from its one and only re-fit. Most, too, bear a nameplate of an illustrious former occupant: choose from Agatha Christie, Leon Trotsky, Jacqueline Onassis, Greta Garbo, Mata Hari...

 Hotel Pera Palas, Mesrutiyet Caddesi 98/100 Pera Palas Hotel ).

Tip
To phone from the UK, omit the first zero of numbers given and prefix with 00 90.

Shopping
Carpets, kilims, antique lanterns, brightly painted ceramics, cotton table cloths, fake Prada handbags, cow-hide rugs, Ottoman silverware; there's no shortage of goods to buy, with the best selection often in the Grand Bazaar. Ideally, particularly for carpet-shopping, you should check out prices at home first, but aim to pay half the first quoted price, keep smiling, and settle for whatever you can get. Haggling is not an art; it's a test of wills. Sisko Osman's (, in the tranquil sanctuary of the Zincirli Han in the north-east of the bazaar, has a good selection of new, semi-old, and antique kilims and carpets.

Useful information
Time Out: Istanbul (£10.99) is the best guidebook for restaurants and nightlife, although it has very few details on any of the monuments. For sightseeing, the new edition of the Rough Guide: Turkey (£14.99) is more informative but weighty.

The Turkish Tourist Office in London offers an information service on 020 7355 4207, and operates a 60p-a-minute brochure line, 09001 887755. Useful websites include.

In Istanbul itself, there are tourist information booths dotted around, most usefully in Sultanahmet Square where you can pick up various maps and leaflets - open daily 9am-5pm. The monthly Time Out magazine (£1.70) has a semi-literate English-language insert, useful for listings and details of new restaurants.