Exceptionally well preserved, the watchtower of Sant Llorenç de la Muga is isolated on top of a hill close to the town, which dominates along with a large part of the valley. It is documented in the year 1292. With a circular plan, it is about 12 m high and has three floors, the two lower ones covered with a dome, open with loopholes. The door, with a monolithic lintel, is raised 1 m from the ground. It is a work of the 13th century. It has been modernly restored and some corbels, which served as a support for some wooden fortification, have been redone.