Secret Room Found Behind Bookcase Door | StashVault - Secret Stash Compartments
Door Hidden as Bookcase

Bookcase Pivots to Reveal Staircase and Secret Room

Swing-out Bookcase Door

Built-in Bookcase Opens as Door

A user on Reddit uploaded pics to this Imgur gallery of a secret bookcase door they found in their house. Kids were playing and found out this bookcase pivoted out to reveal a spiral staircase behind. Half way down the staircase is a secret crawlspace that some unknown person had been recently living in.