Saint Alexander’s church in Rinsumageast was built of tuffstone originally in the 11th century. The semicircular choir was built in the 12th century followed by the nave and the tower dates from the 13th century. Under the choir is a crypt, uniek for the north of the Nederlands. The church was enlarged in ca. 1525 with the replacement of the southern aisle by a new one. The monumental Pipe organ was built in 1892 by Bakker & Timmenga.
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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.