The Drunkard's Tower is one of the three remaining towers of Moat Cailin, the others being the Gatehouse Tower and the Children's Tower. It is called the Drunkard's Tower due to its great lean. It stands where the south and west walls once met.
A Game of Thrones
A Dance with Dragons
During the siege of Moat Cailin, Ramsay Bolton sends Theon Greyjoy to offer the ironborn garrison of Moat Cailin food and safe passage if they surrender to House Bolton unarmed. Theon passes by the Drunkard's Tower to enter the Gatehouse Tower, where the majority of the garrison are. He discovers eighteen ironmen still hold the Drunkard's Tower.