As well as cleaning, receiving post, and providing comfort and security to her residents, María has invaluable long-term knowledge of her building. She knows every square inch, who has lived here and who has died here. She knows things you wish you knew, and things you’re glad you don’t.

La cárcel de Carabanchel, Europe’s biggest and most notorious prison until its closure in 1998, was built under General Franco’s watch. Between 1940 and 1944, every wall was raised and every metal door was fitted by the same prisoners who would eventually do their time here. None dared lay a brick loosely or leave a screw untightened – this prison was a star-shaped fortress, and nobody was escaping.