A prison situated in the Sleeping Kingdom. Home to the most dangerous criminals in the kingdoms. The prison was not affected by the Sleeping Curse, and is not affected by the Enchantress' thornbush spell either. Enchanted wooden soldiers guard the prison.
The Thirteenth Floor : Cell of Rumplestiltskin. Has two barred windows, one on his door and one facing Mermaid Bay, both too high for him to look through. Rumplestiltskin used to grow a small flower inside. He is broken out of prison by Ezmia in The Enchantress Returns.
The Masked Man's Cell : at the very top of the prison. A plaque on the wall says the Masked Man is imprisoned for life for attempted robbery of the Fairy Godmother, and by the time he is freed, he has been imprisoned for "over a decade". When Alex and Conner look inside his cell, they see illustrations of winged creatures, pirate ships, and animals with big ears and feet. He has carved lumps of coal into hooks, hearts, and swords.
In A Grimm Warning, General Marquis and his army break into the prison and defeat the wooden soldiers, burning them (and their parts) in a bonfire. They offer the prisoners (including the Masked Man) the chance to join the Grande Armée. When the General is defeated, the prisoners and what is left of the Armée is rounded up by Jack and Goldilocks and reimprisoned.