So-called Tallinn Gate is the only remaining 17th century gate of the city wall in Baltic Countries. It was built between 1675 and 1686 and designed probably by Swedish Erik Dahlberg. During the teardown of the fortification in the 19th century only the Tallinn Gate was preserved, as well as the embankments and the trench that leads to the Venuse Bastion at the riverside - the so called Vallikäär.
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.