This is a pool from an abandoned orphanage, formerly run by the Großes Waisenhaus BMV Stiftung (Great Orphanage BMV Foundation) in Braunschweig, Germany. The foundation has been around for more than 750 years, but ran into a severe financial crisis in the last ~decade. As a result, this orphanage was closed down in 2004. Nine years later, it looks like the buildings are being prepared to be demolished, as they're almost done being cleaned out. Not much left, other than concrete and bricks at this point. And a really old, mangled baby stroller.