This is an older secret bookcase door, and a bit less sneaky than some. You can see where the edges of the door line up and would pivot. In a dark office or library, it would still seem pretty concealed.
These sliding bookcases move to reveal additional storage space behind. This method could also be used for a moving bookcase entry or doorway, though these have highly visible rails.
Here’s a well hidden bookcase door in both open and closed positions. All the shelves being trimmed out to be extra thick gives additional tolerances to incorporate a door like this. If anyone knows the original source for these pics, let me...
