Hagia Sophia, the Church of the Holy Wisdom, was built in just five years, from 532 to 537, for the Byzantine emperor Justinian I by the architects Anthemius of Tralles and Isidore of Miletus. Its great dome, about 31 metres across and 55 metres above the floor, seems to float on a ring of windows. For more than 900 years it was the main church of the Byzantine Empire. After Sultan Mehmed II conquered the city in 1453 it became a mosque, and the minarets were added. It was a museum from 1935 and has been a mosque again since 2020. It is part of the Historic Areas of Istanbul UNESCO World Heritage Site. Foreign visitors need a ticket and see the interior from the upper gallery; it closes to visitors at prayer times, and shoulders, knees and, for women, hair must be covered. Walk this order. The outer court → the narthex → the central dome → the view from the upper gallery → across the square to the Blue Mosque, 3 minutes.

The Sultan Ahmed Mosque, known as the Blue Mosque, was built from 1609 to 1616 for Sultan Ahmed I by the architect Sedefkâr Mehmed Ağa, a pupil of the great Sinan. It is famous for its six minarets and for the cascade of domes and half domes that rise over the prayer hall. Inside, more than 20,000 hand made İznik tiles in blue, green and white cover the walls and give the mosque its nickname. The large courtyard has a central ablution fountain. On its west side lies the old Hippodrome of Constantinople, with the Egyptian obelisk raised there in 390 and the bronze Serpent Column. Entry is free; it closes to visitors at prayer times, and the same dress code applies as at Hagia Sophia. Walk this order. The courtyard and the ablution fountain → the prayer hall and its carpets → the cascade of domes → the blue İznik tiles → out to the Hippodrome, then 5 minutes north to the Basilica Cistern.

The Basilica Cistern is a vast underground water reservoir built in the 6th century under Emperor Justinian I to store water for the Great Palace and the city. Its roof rests on 336 marble columns in 12 rows, many of them reused from older buildings, and the hall is about 138 metres long and 65 metres wide. Walkways lead over the shallow water between the lit columns. In the far corner, two columns stand on carved heads of Medusa, one placed sideways and one upside down. The cistern needs a ticket; queues are shortest early in the morning. Walk this order. Down the entrance stairs → the forest of columns → the Medusa heads → back along the reflections path → 7 minutes north east past Hagia Sophia to the Imperial Gate of Topkapı Palace.

Topkapı Palace was the home and seat of government of the Ottoman sultans for almost 400 years. Mehmed II began it in the years after the conquest of 1453 on the tip of the old city, where the Bosphorus, the Golden Horn and the Sea of Marmara meet. It is not one building but a chain of courtyards and pavilions. The Imperial Gate opens into the First Court, around the Byzantine church of Hagia Irene; the inner courts hold the council chamber, the treasury with its jewelled daggers and diamonds, the kitchens, and the Harem. The sultans moved to Dolmabahçe Palace in 1856, and Topkapı became a museum in 1924. From the terraces at the far end you look out over the Bosphorus to Asia. The First Court is free; the palace needs a ticket, and the Harem has its own. Walk this order. The Imperial Gate → the First Court → the palace courtyards → the terraces over the Bosphorus → tram T1 from Gülhane to Beyazıt-Kapalıçarşı for the Grand Bazaar, about 15 minutes.

The Grand Bazaar, the Kapalıçarşı, is one of the largest and oldest covered markets in the world. It grew from a domed hall built under Mehmed II soon after 1453 into a city of its own, with about 60 covered streets and some 4,000 shops under painted vaults. Kalpakçılar Caddesi, the main street, is lined with jewellers and gold dealers, and the side lanes hold carpets, lamps, leather, ceramics and textiles. Old caravanserais called hans open off the streets into quiet inner courtyards where craftsmen still work. Bargaining is expected. Free entry; closed on Sundays. Walk this order. In through the Beyazıt Gate → down Kalpakçılar Caddesi → the jewellery and craft lanes → a pause in an inner courtyard → 15 minutes downhill through the market streets to Eminönü and the Spice Bazaar.

The Spice Bazaar, also called the Egyptian Bazaar (Mısır Çarşısı), was built in the 1660s as part of the New Mosque complex at Eminönü, and its rent helped pay for the mosque. The L-shaped hall has arched, vaulted streets lined with stalls of spices, dried fruit, nuts, Turkish delight, tea, coffee and dried herbs. Next to it, the New Mosque (Yeni Cami), finished in 1665, faces the Golden Horn and the Galata Bridge. Around the outside, more stalls run towards the waterfront and the ferry piers. Free entry. Walk this order. From the New Mosque → into the main arched hall → the spice stalls → the stalls on the waterfront side → over the Galata Bridge to Karaköy and up to the Galata Tower, about 20 minutes.

The Galata Tower rises over the old Genoese quarter on the north side of the Golden Horn. The Genoese built it in 1348 as part of the walls of their colony, and at about 67 metres it was long the tallest building in the city. Over the centuries it served as a watchtower, a prison and a fire lookout. A lift and stairs lead to the gallery that runs around the top, with a panorama over the Golden Horn, the old city’s domes and minarets and the Bosphorus. The tower needs a ticket and queues can be long around sunset; the steep lanes around it are full of cafés. Walk this order. Up from Karaköy → the tower from its square → the upper gallery → the Golden Horn panorama → down to the Bosphorus shore at Karaköy, 10 minutes.

The Bosphorus is the strait, about 31 kilometres long, that joins the Black Sea to the Sea of Marmara and divides Istanbul between Europe and Asia. From the waterfront at Karaköy and Kabataş you can watch ferries, fishing boats and huge cargo ships pass, with the Asian shore and the Maiden’s Tower opposite. Public ferries cross to Üsküdar and Kadıköy for the price of a transit card fare, and longer Bosphorus cruises run up the strait past wooden mansions, palaces and the fortress of Rumeli Hisarı, built in 1452 before the conquest. The Bosphorus Bridge, opened in 1973, was the first bridge between the two continents. The shore is free. Walk this order. The waterfront promenade → a ferry or the view to the Asian shore → the shoreline fortresses → the bridge views → continue along the shore to Dolmabahçe Palace, about 20 minutes on foot or one tram T1 stop to Kabataş.

Dolmabahçe Palace was built from 1843 to 1856 for Sultan Abdülmecid I by the architects of the Balyan family, on land reclaimed from the Bosphorus; its name means filled garden. It replaced Topkapı as the main residence of the sultans and mixes Ottoman forms with European Baroque and Neoclassical style, with a seafront about 600 metres long, gilded ceilings and huge crystal chandeliers in the Ceremonial Hall. Mustafa Kemal Atatürk, founder of the Turkish Republic, died here on 10 November 1938, and the palace clocks were stopped at 9:05, the time of his death. The clock tower by the entrance dates from the 1890s. The palace is visited on guided tours with a ticket and is closed on Mondays. Walk this order. The seaside gates → the ceremonial façade → the palace gardens → the clock tower grounds → about 30 minutes along the shore road, or a short bus ride, to Ortaköy.

The Ortaköy Mosque, officially the Büyük Mecidiye Mosque, stands on a quay jutting into the Bosphorus. It was built from 1854 to 1856 for Sultan Abdülmecid I by the Balyan family, the architects of Dolmabahçe, in an ornate neo-Baroque style with tall windows that fill it with light reflected from the water. Behind it, the Bosphorus Bridge crosses to Asia, one of the classic views of Istanbul. The little square next to it is lined with cafés and stalls selling kumpir, baked potatoes with fillings, and waffles, and is busy with locals on weekends. Entry is free; it closes to visitors at prayer times. Walk this order. The waterfront square → the mosque on the quay → the bridge behind it → the façade up close → a quiet moment on the waterfront → end of the tour; buses run back along the shore to Kabataş for tram T1.