A moratorium is in effect on adding information from Fire and Blood until December 20th.
Tumbledown Tower is an ancient watchtower in the wolfswood in the north that has been abandoned for a long time. The stones that make the tower have fallen from their places and are overgrown with moss and ivy. The vault still stands, and there are no villages nearby.
A Storm of Swords
Bran Stark, Hodor, and Jojen and Meera Reed rest in the tower's vault on their journey north to the Wall. Although its true name has been lost, Bran names it the "Tumbledown Tower" for its appearance.