I'd call it a
"Fortress of Solitude for babies."
The Big Bang Theory Season 10, Episode 6
We are about to enter Atzel's FORTRESS.
The Big Bang Theory Season 2, Episode 3
Welcome to my FORTRESS of solitude.
The Big Bang Theory Season 8, Episode 7
Welcome to my FORTRESS of shame.
The Big Bang Theory Season 9, Episode 19
Casterly Rock
is an impregnable FORTRESS.
Game of Thrones Season 7, Episode 3