Sightseeing in Istanbul divides along the water. On the European side, Sultanahmet holds most of what people travel for: Hagia Sophia, finished in 537 and serving in turn as church, mosque, museum and mosque again; the Blue Mosque facing it across a garden; Topkapı Palace above the point where the Bosphorus meets the Golden Horn; and the Basilica Cistern, a sixth-century underground reservoir carried on 336 columns. All of it sits within a twenty-minute walk, which is why almost every guided route starts here.

North of the Golden Horn the city changes register. The Galata Tower, built by Genoese merchants in 1348, presides over a district of steep lanes climbing toward Istiklal Avenue and its red heritage tram. The Grand Bazaar and the Spice Bazaar stay on the old peninsula, both closed on Sundays. Süleymaniye Mosque, Sinan's work, gives the best free view over the Horn. Balat and Fener further upstream are quieter: coloured houses, laundry lines, and stairs instead of boulevards. The Asian side is twenty minutes away by ferry, and Kadıköy with the Moda neighbourhood is where the city stops performing for visitors.

Practical: mosques close to visitors during the five prayer times and for longer around Friday midday, so build that into the day. Shoulders and knees stay covered, women cover their hair with a scarf handed out at the door, and shoes come off. A Museum Pass pays for itself from the third site; an Istanbulkart covers ferries, trams and funiculars and is worth buying on arrival. April to June and September to October are the walking months. In July and August the queues at Hagia Sophia and Topkapı are the longest of the year, and only the early morning is bearable.