Tate Modern

The lowdown

Tate Modern is a decommissioned power station on the south bank of the river, turned into the most visited modern art gallery in the world. The permanent collection is free, which means Picasso, Rothko, Warhol and a Turbine Hall the size of an aircraft hangar all cost you precisely nothing.

Start down in the Turbine Hall, where there is usually a huge free installation you can walk through or under. Then take the lifts up. The collection is split across two buildings joined by a bridge, and you can drift between them for hours without spending a penny.

Here is the bit most people miss. Head up the Blavatnik building at the back. The upper-floor landings and bar give you a free, wide, head-on view across the river to St Paul's, the Millennium Bridge below and the whole City skyline behind it. Better than half the paid platforms in town.