Hagia Sophia was built as a cathedral by the Byzantine emperor Justinian I and completed in 537. Its huge dome, about 31 metres across, seems to float above a ring of windows and was an engineering wonder for nearly a thousand years. After the Ottoman conquest in 1453 it became a mosque, then a museum in 1934, and a mosque again in 2020. Byzantine mosaics and Islamic calligraphy share its interior.

The Sultan Ahmed Mosque, known as the Blue Mosque, was built between 1609 and 1616 for Sultan Ahmed I. It faces Hagia Sophia across Sultanahmet Square. It is the only mosque in Istanbul with six minarets, and its cascade of domes rises over a large courtyard. Inside, more than 20,000 handmade Iznik tiles in blue and green patterns give the mosque its nickname.

The Hippodrome of Constantinople was the chariot racing stadium and centre of public life in Byzantine times. Its outline is now Sultanahmet Square. Three monuments remain along its spine: the Egyptian Obelisk of Theodosius, carved around 1450 BC, the bronze Serpent Column from ancient Delphi, and the Walled Obelisk. The German Fountain stands at one end.

The Basilica Cistern is a huge underground water reservoir built in the 6th century under Emperor Justinian I. Its roof is held up by 336 marble columns arranged in rows, many taken from older buildings. Walkways cross the shallow water in dim light. Two columns at the back stand on carved Medusa heads, one sideways and one upside down. It was restored and reopened in 2022.

Gülhane Park was once part of the outer gardens of Topkapı Palace and opened as a public park in 1912. It stretches down the slope from the palace towards the Bosphorus. Tall plane trees shade its paths, and in spring it is filled with tulips. At the far end, the Goths' Column from Roman times stands, and tea gardens look out over the water.

Topkapı Palace was the main residence of the Ottoman sultans for about 400 years, from the 1460s to the 1850s. It stands on a point above the Bosphorus and the Golden Horn. Its courtyards lead to the Imperial Council hall, kitchens, the harem and pavilions with fine tiles. The treasury displays the Topkapı Dagger and the Spoonmaker's Diamond, and holy relics are kept in another chamber.

The Istanbul Archaeology Museums are a group of three museums in the outer garden of Topkapı Palace, opened in 1891. Their collection holds over a million objects from across the former Ottoman lands. Highlights include the Alexander Sarcophagus, the Treaty of Kadesh tablet and the Siloam inscription. The Tiled Kiosk, built in 1472, displays Turkish ceramics.

The Grand Bazaar is one of the largest and oldest covered markets in the world. Its core was built after 1455, soon after the Ottoman conquest, and it grew into a maze of more than 60 streets and about 4,000 shops. Under painted vaults, traders sell carpets, jewellery, ceramics, lamps, leather and spices. Old caravanserais called hans surround the main halls.

The Süleymaniye Mosque crowns the third hill of Istanbul above the Golden Horn. It was built between 1550 and 1557 by the great architect Mimar Sinan for Sultan Süleyman the Magnificent. Its large dome and four minarets dominate the skyline. The complex included schools, a hospital and a soup kitchen. Süleyman and Sinan are both buried in tombs nearby.

The Rüstem Pasha Mosque is a small mosque near the Spice Bazaar, built around 1563 by Mimar Sinan for Rüstem Pasha, grand vizier and son-in-law of Süleyman the Magnificent. It stands on a raised platform above shops. It is famous for its interior, almost completely covered with Iznik tiles in floral and geometric patterns, among the finest in the city.

The New Mosque, Yeni Cami, stands at the southern end of the Galata Bridge in Eminönü. It was begun in 1597 by Safiye Sultan but completed only in 1665. Its cascading domes and two minarets face the Golden Horn and are a landmark of the waterfront. The square in front is busy with pigeons, ferry passengers and street sellers.

The Spice Bazaar, also called the Egyptian Bazaar, was built in the 1660s as part of the New Mosque complex near the Galata Bridge. Its rent helped pay for the mosque. Its L-shaped covered hall is lined with stalls piled with spices, dried fruits, nuts, Turkish delight, teas and soaps. Fresh food shops and cafes fill the streets around it.

The Galata Bridge crosses the Golden Horn, linking the old city at Eminönü with Karaköy. Bridges have stood here since the 19th century; the present one opened in 1994. Fishermen line its upper deck day and night, dropping lines into the water, while fish restaurants fill the lower level. The bridge gives fine views of the mosques and the Galata Tower.

The Galata Tower is a medieval stone tower in the Beyoğlu district, built by the Genoese in 1348 as part of their walled colony. It is about 67 metres tall. Over the centuries it served as a fire watch tower and a prison. Its viewing gallery gives one of the best panoramas of Istanbul, across the Golden Horn to the old city and the Bosphorus.

İstiklal Avenue is a pedestrian street about 1.4 kilometres long in the Beyoğlu district, running from Taksim Square to Tünel. Lined with 19th-century buildings, it holds shops, cafes, churches, consulates and passages such as Çiçek Pasajı. A red nostalgic tram runs along its length. Millions of people walk it on busy weekends.

Dolmabahçe Palace stands on the European shore of the Bosphorus. Built between 1843 and 1856 for Sultan Abdülmecid I, it replaced Topkapı as the main residence of the Ottoman sultans. Its style mixes Baroque, Rococo and Ottoman elements, with lavish use of gold and crystal. Its great ceremonial hall has a huge chandelier. Atatürk died in the palace in 1938.

The Ortaköy Mosque stands right on the water's edge of the Bosphorus, at the foot of the Bosphorus Bridge. It was built in 1856 in Neo-Baroque style for Sultan Abdülmecid I. Its tall windows fill the interior with light. The square around it is full of cafes and stalls selling baked potatoes and waffles, and it is a favourite place to photograph the bridge.

The Bosphorus Bridge, officially the 15 July Martyrs Bridge, was opened in 1973 and was the first bridge to link Europe and Asia across the Bosphorus. The suspension bridge has a main span of 1,074 metres. At night it is lit with changing colours. Ferry and boat cruises pass beneath it, giving views of the palaces and mansions along the shores.

Rumeli Fortress stands on the European shore of the Bosphorus at its narrowest point. Sultan Mehmed II built it in just a few months in 1452, before the conquest of Constantinople, to control ship traffic on the strait. Its three great towers and walls climb a steep slope. It is now a museum, and its walls give views across to the Asian shore.

Beylerbeyi Palace stands on the Asian shore of the Bosphorus, near the Bosphorus Bridge. It was built in the 1860s for Sultan Abdülaziz as a summer residence and a place to host foreign guests. Its white marble facade faces the water, with two small bathing pavilions on the shore. Inside are fine chandeliers, carpets and a pool in the main hall.

The Çamlıca Mosque stands on Çamlıca Hill on the Asian side of Istanbul. It opened in 2019 and is the largest mosque in Türkiye, able to hold over 60,000 people. Its six minarets and large dome follow classical Ottoman design. The complex includes a museum of Islamic art, a library and an art gallery. The hill gives wide views over the city.

The Maiden's Tower stands on a tiny island at the entrance to the Bosphorus, off Üsküdar. A tower has stood here since ancient times; the present building dates mostly from the 18th century. Legends tell of a princess placed here to escape a prophecy. It has served as a lighthouse and customs station. Restored in 2023, it is now a museum reached by boat.

Balat is an old neighbourhood on the Golden Horn in Istanbul, once home to large Jewish and Greek communities. Its steep streets are lined with colourful wooden and brick houses, churches, synagogues and small cafes. Nearby Fener holds the Ecumenical Patriarchate and the red brick Phanar Greek Orthodox College. It is a popular place for photography.

The Chora Church is a Byzantine church near the old city walls of Istanbul. Its present form dates mostly from the early 14th century. It is famous for some of the finest surviving Byzantine mosaics and frescoes, showing the lives of Christ and the Virgin Mary. It became a mosque in the Ottoman period, then a museum, and reopened as a mosque in 2024.

Pierre Loti Hill rises above the end of the Golden Horn in the Eyüp district. It is named after the French writer Pierre Loti, who loved Istanbul and is said to have spent time at the cafe here in the late 19th century. A cable car climbs from the shore past an old cemetery. The terrace cafe offers a famous view down the Golden Horn.