The Prison of the Star Queen
A fey prison made by their leader, Titania. Few know who resides within it's walls, or how it works.
Purpose / Function
The trees root structure acts a prison for powerful enemies of the Fey.
Architecture
The structure resembles a root structure of a tree, with a trunk a few thousand feet in diameter. The top half of the tree is dead and withered, but beaneath the surface the root structure continues outward into an empty space in the ground of the Material Plane. The roots surround the entire empty space, forming walls.
The roots themselves are thick enough to be traversed by a medium sized creature, but no one other than the upper eschelon of Fey society are allowed within the tree itself.
History
After being cursed, Hector the Stalwart returned to the lands of the fey to attempt to cure his and his fellow knights cursed forms. During the fight with Titania she realzied her people would lose against his now powerful cursed form and sacrificed herself and entrapped him in a tree to match his size, killing herself in the process.
Hector remains there, trapped in the tree and in agony.