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.
Sirmione castle was built near the end of the 12th century as part of a defensive network surrounding Verona. The castle was maintained and extended first as part of the Veronese protection against their rivals in Milan and later under the control of the Venetian inland empire. The massive fortress is totally surrounded by water and has an inner porch which houses a Roman and Medieval lapidary. From the drawbridge, a staircase leads to the walkways above the walls, providing a marvellous view of the harbour that once sheltered the Scaliger fleet. The doors were fitted with a variety of locking systems, including a drawbridge for horses, carriages and pedestrians, a metal grate and, more recently, double hinged doors. Venice conquered Sirmione in 1405, immediately adopting provisions to render the fortress even more secure, fortifying its outer walls and widening the harbour.
Thanks to its strategical geographical location as a border outpost, Sirmione became a crucial defence and control garrison for the ruling nobles, retaining this function until the 16th century, when its role was taken up by Peschiera del Garda.