Biskops-Arnö was a palatial residence of the archbishop of Uppsala, built in the first half of the 1300s. After the Reformation it was left to decay and finally demolished in the early 1700's, when the present main building was erected. For nearly 200 years Biskops-Arnö was a seat of Colonel in the Royal Regiment.
In 1956 Biskops-Arnö moved to the foundation of the Association of the Nordic Institute, who placed there a Nordic education institute and a college. Biskops-Arnö is a great destination that offers both nature and culture. Make sure to visit the Gothic hall, a room with limestone player and grand pillars - a remnant of the old bishop's castle. Visiting groups can book a meal or coffee at Biskops-Arnö college who also have hostel during the summer.
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.