CaixaForum Madrid

A former power station reworked into a cast-iron-and-rusted-steel cultural centre, fronted by Patrick Blanc's 24-metre living vertical garden, one of the most photographed walls in the city. Rotating contemporary art and photography exhibitions inside, no permanent collection.

The building appears to float above the plaza: the architects cut away the ground floor and excavated underneath it, a deliberately disorienting entrance sequence that's worth pausing to notice before heading in. The vertical garden outside is free to view and photograph at any time, even without a ticket to the exhibitions. It sits directly across from the Prado's Paseo del Prado entrance, making it an easy add-on to a Golden Triangle museum day.