Only foundations and one gate-tower have survived of the so-called fortified Tafelgut that used to belong to the bishop of Tallinn.
The castle was erected on a hill by the Porkuni lake in 1479 by Simon von der Borch. Cannon towers stood in the corners of the camp castle shaped as an irregular rectangle. The circular wall and the towers did not probably reach their height all at the same time, but in the course of a longer period. This claim is backed up by the gate tower - rectangular at the bottom and octagonal at the top. The machicolation frieze adorning the top of the tower dates back to a much later time, as proved by comparing the engravings of Porkuni produced in the 17th and 19th centuries. The castle was severely damaged during the Livonian War. The castle tower currently houses museums.
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.