Either Lütold V von Regensberg or his son Ulrich established the fortified town of (Neu)-Regensberg around 1250. Ulrich died around 1280, and his son Lütold VIII had to sell Regensberg to Habsburg-Austria in 1302. The Habsburgs mortgaged the castle and town several times, and in 1407 the so-called Herrschaft Regensberg was acquired by the city of Zürich. From 1417 the castle became the seat of the bailiff of the bailiwick of Regensberg. On 6 June 1443 the council of Zürich forced their troops and the citizens to defend the fortified town, three days later the castle was conquered during the Old Zürich War by Zürich's contrahents, but not destroyed, and some months later manned again by Zürich troops.
On 9 September 1540 the town, but not the castle, was destroyed by fire, because it was separated from the Oberstadt by a ditch. The upper castle was rebuilt in the following year. From 1689 the castle and the upper town were fortified according to then modern standards. On 13 March 1798 the French revolutionary troops forced the council of the city republic of Zürich to abdicate, and the country bailiwicks were dissolved. After the end of the short-lived Helvetic Republic, Regensberg became the district capital, and the castle was the seat of the cantonal authorities, and in the main building there was the county jail until 1863.
Regensberg was designed as a fortified castle town and built by then modern contemporary criteria. The so-called upper castle (Oberburg) comprises a rectangular plaza as main square which is surrounded two rows of houses, and into the limestone a 57 m (187 ft) deep water well was carved. The lower castle (Unterburg) or lower town (Unterstadt) was probably built in the 14th century nestled at the castle's hill outside of the town wall. Therefore, it was not involved in the modernization of the upper castle in 1689.
Nowadays, the castle belongs to the Regensberg Castle Foundation. The round tower is still open to the public and offers a spectacular panoramic view of the surrounding region. In addition, information panels inside the tower relate the history of the small country town of Regensberg.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.