Otepää castle hill is the site of an ancient stronghold. It is speculated that a fortified settlement may have existed there even before Christ. The first major extension works were initiated in the 11th and 12th century when the castle was at the crossroads of important trading routes. Herman I, the bishop of Tartu, established there the first stronghold of its diocese. A settlement, which was mainly populated by craftsmen and merchants, appeared around the bishop’s castle in the 13th century. The castle was the first known brick building in Estonia.
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.