The oldest parts of Gerum Church are the choir and apse, dating from circa 1200 and Romanesque in style. The presently visible, Gothic nave dates from a later time of the 13th century and probably replaced an earlier, Romanesque nave. The tower, which was never finished, was built circa 1300. The only non-medieval part of the church is the sacristy, built in 1835.
Gerum Church is constructed of limestone. The exterior is whitewashed apart from several finely carved stone details. The façade is broken by four windows on the southern side while the northern completely lacks windows. The church has three portals, one Romanesque in the choir and two Gothic in the nave and tower, respectively. The Gothic portals are decorated with stone sculptures. Inside, the church carries frescos from at least three different periods: the 13th century, the 15th century (by the Master of the Passion of Christ) and the 18th century. The church also has a decorated stained glass window from the 14th century.
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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.