Castle of Gormaz - Credit: Wikimedia Commons
The Castle of Gormaz (Spanish: Fortaleza de Gormaz or Castillo de Gormaz) is a large castle located in Gormaz, Spain. Its current structure was built in 965 to defend the borders of the Caliphate of Cordoba. At the time of its construction, it was the largest fortress in Europe. Read more on Wikipedia
Source: en.wikipedia.org