St Mary's Church dates from the twelfth century. At this church the Rev. Legh Richmond is thought to have originated the now globally popular idea of using boards with movable numbers to indicate hymn numbers during church services. The 13th-century tower is of a very unusual style in that it is built on four piers at the entrance to the church. This is one of only four in examples in Britain. The tower contains a ring of 8 bells which the heaviest weighs 10.5cwt in the key of G. The oldest bell was made in 1594.
The current church building has aspects dating from the late 12th century onward, with the majority of the present building resulting from the alterations of the 14th and 15th centuries. The Oglander Chapel on the eastern end of the south aisle is the resting place of members of that family and includes two elaborately carved and painted wooden effigies of knights placed upon two of the tombs. Whilst installed by the family itself, their appearance does not represent the accurate historical dress of the time for the family members in the tombs beneath. In the north aisle there are funerary hatchments of the Oglander family on the walls, and two fonts from the 13th and 15th centuries.
The churchyard contains the Commonwealth war graves of four British Army soldiers of World War I.
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.