Letná is a flat green plateau one steep climb above the river, and on its edge a 23-metre red metronome stands on a granite plinth, swinging. From the terrace around it the whole Old Town is spread below, with the Vltava's bridges stitched across it one behind another. Skateboarders work the stone, people drink at the wall, and this is the meeting point half of Prague names when it wants somewhere outdoors.
The plinth was built for something else. A granite group with Stalin at the front stood on it from 1955 until 1962, when the state blew it up and left the base empty. The metronome arrived nearly thirty years after that. Walk west and you come to the cast-iron Hanavský Pavilion, carried up here piece by piece in 1898 from an exhibition held down in Holešovice, its terrace hanging out over the drop. Walk east instead and the park runs level under plane trees for about a kilometre, ending at a beer garden that seats several hundred under the chestnuts.