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.