Belgrade Fortress (Kalemegdan)

A fortress on a ridge above the meeting of the Sava and Danube rivers, fought over by Romans, Byzantines, Ottomans and Austrians, now surrounded by the Kalemegdan park. It's free to wander the walls, gates and towers, with sunset views over the rivers and New Belgrade.

Nearby are the Knez Mihailova pedestrian street, the Bohemian Skadarlija quarter, and the huge white Church of St Sava, one of the largest Orthodox churches in the world, with a dazzling gold mosaic dome.