Margaret's Castle is a small Tower house probably built in the 15th century. Only two storeys still exist but there is evidence that it was at least three storeys high. It is vaulted above the ground floor with a rectangular tower with projecting turrets in the north west wall. The doorway between the turrets was protected by a murder-hole. A spiral stairway rises within the west turret.
Ardglass had at least six castles and remains of four of them can still be seen: Ardglass Castle, Cowd Castle, Margaret's Castle and Jordan's Castle.References:
The city walls of Avila were built in the 11th century to protect the citizens from the Moors. They have been well maintained throughout the centuries and are now a major tourist attraction as well as a UNESCO World Heritage Site. Visitors can walk around about half of the length of the walls.
The layout of the city is an even quadrilateral with a perimeter of 2,516 m. Its walls, which consist in part of stones already used in earlier constructions, have an average thickness of 3 m. Access to the city is afforded by nine gates of different periods; twin 20 m high towers, linked by a semi-circular arch, flank the oldest ones, Puerta de San Vicente and Puerta del Alcázar.