The Matachin Tower is a tower located in the Old Yard in the Citadel complex in the city of Nessus, next to another tower, the Witches' Keep, near the Library. It is inhabited by the Guild of Torturers. The exterior of the tower is decorated with agonized masks.
The name of the tower comes from the fact that the members of the torturers' guild wear masks and dance with their executioners' swords on the feast of Holy Katherine. "Matachins" are the masked sword dancers of Spanish tradition in South America.