Haghia Sophia
Haghia Sophia, known as Aya Sofya and translated as 'Church of Divine Wisdom', is considered the world's finest example of Byzantine architecture. Consecrated in 537AD, its vast dome rises to 56m (183ft), designed to appear suspended in space and thus representative of heaven. So impressed was Mehmet the Conqueror that when he took the city in 1453, he dedicated it as a mosque, and it remained so until declared a museum when the Turkish Republic was founded. Highlights include Byzantine mosaics and huge Ottoman circular shields containing calligraphy of Koranic verses.

Sultanahmet, in front of Topkapi Palace
Tel: (0212) 522 1750.
Opening hours: Tues-Sun 0900-1700 (winter); 0900-1800 (summer) plus first Monday of every month.
Admission charge.

Topkapi Palace
Originally built as a summer residence and the seat of government, Topkapi Palace was home to harem, state administration and military personnel in the 16th century, with around 3,000 residents. Sultans abandoned it for Dolmabahçe Palace in 1855, but many of the sumptuous jewels of the original treasury (including the Topkapi dagger, and gold-plated throne of Murat III), the armoury, silk ceremonial robes, Chinese ceramics and the collection of manuscripts, all convey the old Ottoman decadence. Near the Imperial Gate is Haghia Eirene Museum, venue for concerts during the International Istanbul music festival. The prison-like Harem, comprising several dozen ornate rooms which once housed up to 300 concubines, is only open to guided tours and requires a separate ticket (and separate queue). Weekends and holidays are more crowded.

Babihümayun Caddesi, Sultanahmet
Tel: (0212) 512 0480.
Website: www.topkapisarayi.gov.tr  
Opening hours: Wed-Mon 0900-1600 (winter); Wed-Mon 0900-1900 (summer).
Admission charge.

Kapali Çarşisi (Covered or Grand Bazaar)
The famous and vast bazaar is the best known of Istanbul's markets. It was instated shortly after the 1493 Conquest and contained the slave market, as well as the hans, or caravanserais of old, where Silk Road traders could rest themselves and their camels, as well as sell their goods. While the ornate ceilings and labyrinth-like layout still hark back to the past, these days the vast number of stalls (more than 4,000 of them, in over 60 streets) sell mainly tourist-friendly goods and plasma television screens belie any sense of a timeless atmosphere. The complex also contains two mosques, money change offices, a police station, cafes and an information point. Haggling is essential at most stalls.

Beyazit
Opening hours: Mon-Sat 0900-1900.
Free admission.

Misir Çarşisi (Egyptian or Spice Market)
This L-shaped market, facing the Golden Horn, was built in the 17th century as an extension to Yeni Camii (New Mosque), and financed by the money paid as duty on Egyptian goods. Originally famed for its exotic spices and oils from the Orient, these days it also sells dried fruits, caviar and Turkish delight, as well a plethora of souvenirs at prices generally lower than the Grand Bazaar. Its surrounding streets are a hub of commercial activity, with local craftspeople, traders and a great selection of cheeses and olives.

Eminönü
Opening hours: Mon-Sat 0800-1900.
Free admission.

Sultanahmet Camii (Blue Mosque)
The Blue Mosque was built during the reign of Sultan Ahmet I (1603-1617), as Islam's answer to Haghia Sophia, and remains the symbol and centre of religious demonstrations and Istanbul's only mosque with six minarets. Blue Iznik tiles dominate the interior, and blue light shines through more than 250 windows. The interior is stunning, from the vast central dome designed to lift all eyes heavenward to the latticework-covered Imperial Loge and the mihrab (prayer niche) containing a piece of sacred black stone from Mecca. After dusk during summer there is a Son et Lumière (sounds and lights) show with Turkish, English, French and German on different nights. The Imperial Pavilion also contains the state-run Vakiflar Carpet Museum with Usak, Bergama and Konya samples, dating between the 16th and 19th centuries.

Hippodrome, Sultanahmet
Tel: (0212) 518 1319.
Opening hours: Daily 24 hours, except during some prayer times; Carpet Museum: Tues-Sat 0900-1600, closed 1200-1300.
Free admission.

Yerebatan Sarayi (Basilica Cistern)
Sometimes referred to as the Sunken Palace, the Basilica Cistern was the reservoir for water required for the Byzantine Great Palace, and thought to date back to AD532. This huge atmospheric structure, measuring 140m (460ft) by 70m (230ft), still contains a few feet of water, over which wooden walkways have been constructed. Many of the 335 columns supporting the cathedral-like ceiling have been recycled from pre-Christian temples - such as the Medusa heads that are used as column bases, pilfered from the Temple of Apollo in Didyma (Didim). Rather cheesy piped music spoils the atmosphere to some extent. The cistern was used as a film set for the James Bond film, From Russia With Love (1963).

Yerebatan Caddesi, Sultanahmet
Tel: (0212) 522 1259.
Website: www.yerebatan.com.
Opening hours: Daily 0900-1730.
Admission charge.

Süleymaniye Mosque
Although fewer tourists make it here than to the Blue Mosque, this mosque commissioned by Sultan Sülemaniye I (‘the Magnificent') is even grander and more peaceful, and one of the finest creations by Ottoman architect Mimar Sinan. The huge dome and pencil-slim minarets from each corner of the courtyard are an exquisite essay in symmetry and elegance. Built in the 1550s, the site also contains the tombs of Sinan, Sultan Süleyman I and his wife Roxelana decorated with intricate tiles, the original apartments of the mosque astronomer, charitable foundations, caravanserai and fountain, all set around a tranquil courtyard. There are several outdoor tea-houses in a row behind the mosque in what was formerly known as ‘Addict's Alley'.

Siddik Sami Omar Caddesi, Süleymaniye
Tel: (0212) 513 3608.
Opening hours: Daily 0930-1730. Closed to non-Muslims during prayer times.
Free admission (donation requested).

Galata Kulesi (Galata Tower)
The balcony at the top of Galata Tower has an unforgettable view of the city. Built in 1348 by the Genoese as part of their fortifications, this distinctive 62m (205ft) tower with conical roof is visible from most of the city. It was converted to cater for tourism and has a lift, a nightclub and restaurant on the top floors with a tourist-oriented cabaret that includes belly dancing. On a clear day, the view is spectacular and it is possible to see the main monuments of Istanbul and even the Princes' Islands. It's a good way for visitors to get a feel of the surroundings and there are several charming tea gardens at the foot.

Büyük Hendek Sokak, Tünel
Tel: (0212) 293 8180.
Website: www.galatatower.net
Opening hours: Daily 0900-2000.
Admission charge.

Taksim Square and Istiklal Caddesi
The square is the nucleus of Istanbul's modern European side, which many tourists unfortunately miss. In the southwest corner is the Monument of Independence, where the busy Istiklal Caddesi starts and cuts through Beyoğlu area. This 1.5km (1 mile) pedestrianised boulevard is lined with shops, cinemas, markets and restaurants, and is especially crowded at night. Its 19th-century European consulates, churches and ornate buildings are evidence that Beyoğlu was once the centrepiece for an art nouveau belle époque, and later the hang-out for bohemian artists and intellectuals. Highlights include the stained glass at the entrance to Çiçek Pasaji (Flower Passage), the imposing Galatasaray Lisesi (High School) and various contemporary art galleries (free).

Beyoğlu
Opening hours: Most shops open till 2100, later Fri-Sat.
Free admission.

Greek Orthodox Patriarchate (Fener Rum Patrikhanesi)
The western district of Fener (sadly overlooked by many visitors, yet home to many historical churches) is where you will find the head of the Greek Orthodox Patriarchy, here in Istanbul since the fourth century and in this location since 1601. The actual church within the complex (newly restored after a devastating fire) is called Aya Yorgi (St George). Its interior is opulent dark wood, filled with sacred relics, huge gold-edged paintings and the throne of the Patriarch and St John Chrysostomos, thought to date back to the Byzantine era.

Sadrazam Ali Paşa Caddesi 35, Fener
Tel: (0212) 525 2117.
Opening hours: 0900-1700.

Türk ve Eserleri Müzesi (Turkish and Islamic Art Museum)
Originally the 16th-century palace of Süleyman the Magnificent's most able Grand Vizier, Ibrahim Pasha, this museum contains more than 40,000 items dating from between the seventh to the 19th century. Its famous carpet display contains Turkish carpets depicting Holbein paintings and fragments of 13th-century Selçuk rugs. Further highlights include Ottoman Koran cases and stands, illuminated manuscripts and tiles, and the basement contains an exhibition of the evolution of the Turkish house - from nomadic tents to 19th-century palaces.

At Meydani 46, Sultanahmet
Tel: (0212) 518 1805.
Opening hours: Tues-Sun 0900-1630.
Admission charge.

Arkeoloji Müzeleri (Archaeological Museums)
Istanbul's Archaeology Museums are located in three separate buildings, once part of the Topkapi Palace complex. The main building houses the famous fourth-century BC Alexander sarcophagus discovered in Lebanon, as well as the facade of the Temple to Athena from Assos, Byzantine mosaics and Egyptian and Lycian sarcophagi. The interior of the Çinili Köşk (Tiled Pavilion), built in 1472 by Sultan Mehmet II, is covered in Iznik tiles and contains the 15th-century royal blue Karaman Mihrab (prayer niche). The Museum of the Ancient Orient includes the Treaty of Kadesh, drawn up between the Egyptians and Hittites in the 13th century BC, plus a magnificent sixth-century BC frieze of a bull from the Ishtar Gate of Babylon.

Osman Hamdi Bey Yokuşu, Gülhane
Tel: (0212) 520 7740.
Opening hours: Tues-Sun 0900-1700.
Admission charge.

Istanbul Modern
Located in a restored old waterfront warehouse and opened in 2004, the huge Istanbul Modern has a fine collection of contemporary arts from Turkey and around the world. Specialising in painting and photography, with a cinema screening world films in the basement, the gallery hosts exhibitions that include 20th-century home-grown talent to try to encourage Turkish art. The entire venue is fresh, spacious and well laid-out, with a fine restaurant/cafe on the ground floor overlooking the Bosphorus.

Meclis-i Mebusan Caddesi, Liman İşletmeleri Sahası Antrepo 4, Karaköy 
Tel: (0212) 334 7300.
Website: www.istanbulmodern.org
Opening hours: Tues-Sun 1000-1800, Thurs 1000-2000.
Admission charge; Thurs free.

Yildiz Park
Rising above the area of Beşiktaş, Yildiz is a welcome relief from the noise of the city, with woodland and landscaped gardens. Sultan Abdül Hamit built them for the Çirağan Palace (now a 5-star hotel over the main road) where Sultans strolled and hunted since the 17th century. It is now more popular with courting couples and picnicking families and is busiest at weekends. At the top are Malta Köşkü and Çadir Köşkü, two attractive 19th-century pavilions originally part of the palace, whose guests included Winston Churchill and Charles de Gaulle, and now operating as restaurants and cafes. The park also houses Yildiz Palace Museum, Imperial Porcelain Factory and City Museum.

Yildiz Park, Çirağan Caddesi, Beşiktaş.
Tel: (0212) 258 9020.
Opening hours: Daily, dawn till dusk.
Free admission for pedestrians; charge for taxis.