WALKING through the narrow streets of Istanbul's Old Town, I'm overwhelmed by the smell of roasted chestnuts and fragrant Turkish delight.

The only city in the world to straddle two continents - Europe and Asia - Istanbul is mix of different foods, cultures and religions. It has been the capital of both Christian and Islamic empires, and is now the second city of a secular state.

The seven hills of Istanbul are peppered with mosques, yet the shopping streets of Nisantasi would not look amiss in most Western capitals.

The historic heart of Istanbul is Sultanahmet, where the domes and minarets of the Hagia Sophia dominate the city's skyline.

Once the largest enclosed space in the world, it was originally built in the sixth century as a church to show off the wealth and power of the Christian Byzantine empire.

It then became a mosque in 1453 under the Ottoman emperor Mehmet the Conquerer, before closing its doors in the 1930s and reopening as a museum.

The main nave with its 56m-high dome is breathtaking - not only in terms of scale and its glittering mosaics, but also for being one of the few places in the world where you can see Muslim and Christian iconography sit side by side.

Opposite the Hagia Sophia, is the equally striking Blue Mosque, its instantly recognisable six minarets silhouetted against the sun.

Other highlights of the area include the Ottoman Topkapi Palace, the Hippodrome and the rather unusual Basilica Cistern, a Roman-built columned drain hidden under the streets.

No visit to Istanbul would be complete without a trip to the Grand Bazaar. There are 4,000 shops huddled together in 66 covered streets and alleys, selling every possible thing you can imagine. I even had to use my guidebook map to find my way out, eventually emerging with a bag stuffed full of jewellery, pomegranate tea and Turkish saffron.

Newer areas of the city can be found across the body of water known as the Golden Horn. The Beyoglu is one of Istanbul's main business and entertainment hubs, and the best way to experience modern Istanbul is to sample its wild and hedonistic nightlife.

Hidden on the eighth storey of an apartment block on Istiklal Caddesi is the panoramic and very trendy 360 Istanbul restaurant/bar/cafe.

From the glass-fronted balcony I look out over the Bosphorus Strait, a crucial shipping route between the Black Sea and the Sea of Marmara which divides the city between West and East, Europe and Asia.

I sip a cocktail and watch massive tankers power up the strait, past domes, minarets and old Ottoman palaces.

And this is why Istanbul is so exciting. Being one of the world's oldest urban settlements, it's often described as the "cradle of civilisation", yet it's rapidly becoming a hip and glamorous city break destination.

Like the constant flow of vessels along the Bosphorus, time here refuses to stand still.

Where to stay

Shangri-La Bosphorus, Istanbul

A short distance from the Ottoman-built Dolmabahce Palace, this exciting new hotel is set on the shores of the Bosphorus Strait in the busy Besiktas area of the city.

The elegant classically-styled interior hints at European, Asian and Turkish influences, with more than 1,000 pieces of European and Asian art on display throughout the building.

Yet it is a subtle opulence and the five-star hotel feels luxurious without being overly extravagant. Many of the rooms face onto the water, creating an oasis of calm amid the surrounding urban chaos.

A hammam in the hotel's Chi spa is highly recommended; after being washed and massaged from head to toe guests will leave feeling like an Ottoman sultan.

Where to eat

Kosebasi Nisantasi

Once named the best kebab restaurant in Istanbul by Time magazine, Kosebasi offers traditional South Anatolian cooking in a stylish setting. The Nisantasi branch is the place to have lunch after a day spent shopping in the fashion district. Try the Toros salad (spicy vegetables topped with sour pomegranate syrup), and the Tarsusi minced lamb kebabs are also highly recommended. (www.kosebasi.com/en)

Del Mare

This waterfront restaurant on the Asian side of the Bosphorus is as famous for its view as it is for its fish. It's set in a 200-year-old stone building overlooking the water, and guests can enjoy freshly caught fish while watching local fishing boats pass through the busy strait. (www.del-mare.com/en.html).

Where to party

360 Istanbul

With a panoramic view over the Bosphorus and the Golden Horn, the trendy 360 Istanbul bar/restaurant/club is a place to see and be seen. On the eighth floor of an apartment building in Beyoglu, well-dressed revellers sip cocktails as DJs spin records. It gets busy so book ahead. (360istanbul.com/eng/index1.html)

Reina

This exclusive complex has been popular with Istanbul's bright young things for the past 10 years, and is definitely a place to dance the night away until the early hours. Past celebrity guests have included Madonna, fashion designer Roberto Cavalli and F1 star Felipe Massa. (reina.com.tr/en/)

Travel facts - Istanbul

Natalie Marchant was a guest of the Shangri-La Bosphorus who offer doubles from 297 Euros per room per night (room only). Visit shangri-la.com or call 0800 028 3337.

Turkish Airlines (turkishairlines.com) fly to Istanbul from London and Manchester from £111 return.