The colossal Heidenreichstein castle situated in the moorlands to the northwest of the Waldviertel is the largest and best preserved medieval water castle in Lower Austria. The oldest parts of the castle are dated back to the 12th century. It has never been in enemy hands since its construction. The walls of the four wings, the three corner turrets and the keep are up to four metres thick. A guided tour through the three-storey living apartments with spiral staircase and arcades discloses highly remarkable interior fittings including Gothic furniture, articles of daily life and portrait paintings.
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.