This bookshelf door posted to GardenWeb is mounted on 3 large hinges and swings out to reveal a secret broom closet. The hinges are visible on the right hand side, so it’s not a complete secret. However, it still serves it’s purpose...
This custom bookshelf door was made by Dowd Temple Designs. It doesn’t pivot or slide to the side like many secret doors, but pushes straight back on casters to reveal a large walk-in closet space.