Trelleborg is a collective name for six Viking Age circular forts, located in Denmark and the southern part of modern Sweden. Five of them have been dated to the reign of the Harold Bluetooth of Denmark (died 986). The city of Trelleborg has been named after one of these fortresses. Today Trelleborgen is part of a Viking Age fortress complex, which has been reconstructed. There is a Viking musem with souvenir shop, café and guided tours during the summer. Various events for both children and adults are also arranged during the summer to demonstrate how it must have been to live here in the Viking Age.References:
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.