Probably built in the first half of the 12th century (although some legends say it was built in the 9th century), Sandiás Castle was located over a castrum (Celtic settlement). It participated in the Portugal secession wars (12th century). In 1386 it was assaulted by the duke of Lancaster, pretender to the Castile crown. In the 15th century it was demolished by a popular riot, and rebuilt later. It was a meeting point for troops in the wars with Portugal in the 18th century. There are many legends about this castle.
The Walls of Constantinople are a series of defensive stone walls that have surrounded and protected the city of Constantinople (today Istanbul) since its founding as the new capital of the Roman Empire by Constantine the Great. With numerous additions and modifications during their history, they were the last great fortification system of antiquity, and one of the most complex and elaborate systems ever built. They were also the largest and strongest fortification in both the ancient and medieval world.
Initially built by Constantine the Great, the walls surrounded the new city on all sides, protecting it against attack from both sea and land. As the city grew, the famous double line of the Theodosian Walls was built in the 5th century. Although the other sections of the walls were less elaborate, they were, when well-manned, almost impregnable for any medieval besieger.