HalfBloodBureaucrat reply

Not quite a secret room or space, but when we my parents were doing renovations on our childhood home (the home was roughly 100 years old at the time) they found an old safe (quite small) in the wall that had been left open with a bottle of either port or rum and a long faded note inside. The builder helping dad said it was common to find the odd bottle of alcohol in walls during renos on old homes as there was a tradition for a while where one homeowner leaves a hidden bottle for the next to find during a time of construction/renovations. We couldn't determine how old the bottle was as all the labeling had faded but dad went and bought a new bottle of port and put it in the old safe with a laminated note before sealing it back up, for the next owner to find.