Castello Cova was built between 1910 and 1915 on a design by architect Adolfo Coppedè (brother of the more famous Gino Coppedè), it is an example of Gothic Revival architecture, with guelph-style merlons decorating the external rusticated walls as well as the middle-ages styled tower. The tower of Castello Cova was reportedly an inspiration for the architects of the Velasca Tower, a landmark skyscraper in the centre of Milan. The Pusterla di Sant'Ambrogio, an ancient postern of the Medieval walls of Milan facing Castello Cova, was recreated in the late 1930s in a style that matches the Revival style of the Castello.
References:Sigmaringen Castle was first mentioned in the year 1077 in the chronicles of Petershausen monastery. The oldest parts of the castle are concealed beneath the alterations made during the 17th and the 19th centuries. The secret of the earliest settlement built on this defendable rock will never be fully revealed: large-scale excavation work would be necessary, which the extensive land development renders impossible. Judging from the many Roman remains unearthed in the area around Sigmaringen, the 12th century keep known as the 'Roman Tower' could be traced back to a Roman predecessor.
The castle remains that have been preserved (gate, great hall and keep) date back to the Staufer period around 1200. The castle remains were integrated into subsequent buildings. The foundations of the castle buildings are to a large extent identical to the surrounding castle wall.
These remains give us a good idea of how the castle might have looked during the 12th century.