The original Kaiser Wilhelm Memorial Church on the site was built in the 1890s. It was badly damaged in a bombing raid in 1943. The present building, which consists of a church with an attached foyer and a separate belfry with an attached chapel, was built between 1959 and 1963. The damaged spire of the old church has been retained and its ground floor has been made into a memorial hall. The Memorial Church today is a famous landmark of western Berlin, and is nicknamed by Berliners 'der Hohle Zahn', meaning 'The Hollow Tooth'.
Kaiser Wilhelm II decided to name the church in honor of his grandfather Kaiser Wilhelm I. The foundation stone was laid on March 22, 1891, which was Wilhelm I's birthday. The competition for the design was won by Franz Schwechten who planned for a large church to be built in Romanesque Revival style, including 2,740 square metres of wall mosaic. The spire was 113 metres high and the nave seated over 2,000 people. The church was consecrated on September 1, 1895. By this time of the consecration the entrance hall in the lower section had not been completed. This was opened and consecrated on February 22, 1906. In the Second World War, on the night of November 23, 1943, the church was irreparably damaged in an air raid. The church was largely destroyed but part of the spire and much of the entrance hall survived.
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.