The Dreadfort
The Dreadfort is a castle situated in the North. It was the seat of House Bolton, located on the banks of the Weeping Water east of Winterfell. The Dreadfort is ill-omened as the stronghold of House Bolton, who are famed for the flayed skins of their enemies, often rumored to have been kept on display in the castle, including those of several ancient Stark kings. However, if such gruesome trophies ever did exist they have long since been removed or destroyed.
Following the Battle of the Bastards, House Bolton has become extinct, leaving the Dreadfort without any ruling lordship. However, House Stark only captured Winterfell from the Boltons. No mention is made of the Dreadfort being captured, so it is possible there is still a Bolton garrison holding the castle in rebellion.