entre luces y sombras...

Urban exploration (often shortened as urbex or UE) is the examination of the normally unseen or off-limits parts of urban areas or industrial facilities. Urban exploration is also commonly referred to as infiltration, although some people consider infiltration to be more closely associated with the exploration of active or inhabited sites. It may also be referred to as draining (when exploring drains) urban spelunking, urban rock climbing, urban caving, or building hacking.

The nature of this activity presents various risks, including both physical danger and the possibility of arrest and punishment. Many,^{[citation needed]} but not all, of the activities associated with urban exploration could violate local or regional laws and certain broadly-interpreted anti-terrorism laws or be considered trespassing or invasion of privacy.

Carabanchel Prison was constructed by political prisoners after the Spanish Civil War between 1940 and 1944 in the Madrid's neighbourhood of Carabanchel. It was one of the biggest prisons in Europe until its closure in 1998. The structure followed the panopticon model devised by Jeremy Bentham in 1785.