Spottswood is the seat of House Santagar in Dorne. It appears to be located along the eastern coast. Sylva Santagar is called "Spotted Sylva" because of her freckles, but her friends pretend it is because she is the heir to Spottswood.
During the First Dornish War, after burning Planky Town, Queen Rhaenys Targaryen descended upon Spottswood with her dragon, Meraxes, but as with all other Dornish seats of power great and small, the Targaryens found only old women and children. Nevertheless, those present at Spottswood paid nominal obeisance to the queen.