Koroinen was the residence of Bishop of Finland between years 1229 and 1300. in 1300 the bishop seat was moved couple of kilometres further down the River Aura, to the present-day Cathedral of Turku. There were at least two wooden churches in Koroinen built in the 14th century. The latest one was probably a stone church. It was later destroyed by the Victual Brothers in 1396.
Archaeologists have found remains of three wall grounds, which were probably part of the church. Today there are a white, wooden memorial cross and some stone foundations still remaining on site. The landscape of the site is anyway unique in Finland. You can see three medieval church from there: The Turku Cathedral, St Mary's Church and St. Catherine's Church.
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.