I don't know about you, but I will never outgrow my child-like desire to have secret passages and hidden rooms in my house. This sliding door bookshelf may be one of the most clever and least destructive ways to accomplish this we've seen yet.
We've featured hidden door bookcase hacks before. However, this one not only requires minimal major modification to the home itself, it saves space by using a sliding door design. As secret doors go, it's one of the more clever implementations around.