The Oosterkerk ('eastern church') is a Dutch Reformed church built in the period 1669-1671 by architect Daniël Stalpaert and completed by Adriaan Dortsman. The church bells were cast by Pieter Hemony. The church has not been used for church services since 1962, and fell into decay since then. It was restored in the 1980s.
The layout of the church is in the shape of a Greek cross in which the space between the arms has been partially filled by lower volumes. On the canal side is the main entrance, the elevation of which is supported by a balustrade. The cornice of the lower volumes follows the relief of the walls, whereas the cornice of the Greek cross strictly conforms to the layout without acknowledging the indentations of the wall.
Some 500 people were buried in the church, including Adriaan Dortsman.References:
The Petersberg Citadel is one of the largest extant early-modern citadels in Europe and covers the whole north-western part of the Erfurt city centre. It was built after 1665 on Petersberg hill and was in military use until 1963. It dates from a time when Erfurt was ruled by the Electors of Mainz and is a unique example of the European style of fortress construction. Beneath the citadel is an underground maze of passageways that can be visited on guided tours organised by Erfurt Tourist Office.
The citadel was originally built on the site of a medieval Benedictine Monastery and the earliest parts of the complex date from the 12th century. Erfurt has also been ruled by Sweden, Prussia, Napoleon, the German Empire, the Nazis, and post-World War II Soviet occupying forces, and it was part of the German Democratic Republic (East Germany). All of these regimes used Petersberg Citadel and had an influence on its development. The baroque fortress was in military use until 1963. Since German reunification in 1990, the citadel has undergone significant restoration and it is now open to the public as a historic site.