Sisterton is a town in the Three Sisters, a three-island archipelago located in the Bite, which are considered part of the Vale, thus falling under the authority of House Arryn. Sisterton is located on the middle island of the archipielago
In the books
In the A Song of Ice and Fire novels, Sisterton is located in the same point, the island of Sweetsister. It is the chief port of the Three Sisters and serves as the seat of House Borrell, which rules the island from the castle of Breakwater. House Borrell's overlords, House Sunderland, which rules over the Three Sisters, also resides on Sisterton. The town is also considered the most notorious smuggler's den in all of Westeros. In centuries past, it was a pirate's den.
Sisterton is a small, mean town, rank with the odors of pig waste and rotting fish. Its streets are made of mud and planks, while its are houses daub-and-wattle hovels roofed with straw. By the Gallows Gate there are always hanged men with their entrails dangling out.