Hagby Church is one of Sweden's few preserved round churches, and is considered by many to be the best preserved one in the country. The predecessor of Hagby stone church was the wooded Saint Sigfrid chapel, which was located about two kilometres south of the present church structure. The construction of this stone church began in the late 12th century. By 1541 it was abandoned.
The structure was meant to serve both as a sanctuary and a fortified building. As a result, the upper part of the walls has openings for shooting and spear throwing. The most recent renovation has attempted to emphasize the old nature of the building, so that it is now perhaps the best example of round church architecture, which otherwise is generally mostly found on the island of Bornholm. The triumph crucifix and font dates from the Middle Ages, but the interior is mainly from the 17th and 18th centuries.
References: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.