The city beneath the city

Beneath the crossing where you're standing lies a metro station from 1919, designed by Antonio Palacios, and during the war years it served as a shelter and as a place to live, because anyone who lost their home to a bomb could find refuge down below.

Madrid was the first major city in the world to be systematically attacked from the air, and within a few months it had to work out how to live with that, which turned metro stations, cellars and purpose-dug shelters into a second city beneath the first, with its own rules about who slept where.

The entrance you're looking at now is younger than all of that, because the elegant pavilion Palacios built here was torn down in the seventies, and part of it then moved to his home village in Galicia, in Spain's green northwest.

We carry on a little further east, as far as number 12, where you'll find a revolving door set into the facade.