The Herten family, vassals of the Werden Abbey, was first documented in 1286. At that time, their residence was probably in the center of today's city next to St. Antonius church. In the 14th century, the family with 'Ritter' (knight) status built a fortified house on the site of today's castle. In 1376, this building was mentioned as fief of Werden Abbey. Through marriage, the Herten house fell into the possession of the von Galen family in mid-14th century. In 1488, it changed hands in the same manner to Dietrich von Stecke zur Leythe. Ultimately, in 1529 Anna von Stecke married Betram I. von Nesselrode. As part of the powerful house of Nesselrode, he was steward for the Electorate of Cologne in the Recklinghausen district and expedited the modification and extension of the buildings in 1530.
While foundations of today's main castle building incorporate elements from the 14th-century building, the buildings visible today were built by Stecke and Nesselrode families in the 16th and 17th century. The main castle consists of four wings creating an inner courtyard.
After the First World War, the main castle building was no longer used as a residence and started to deteriorate. Subsidence caused by the widespread sub-surface mining in the surrounding industrial Ruhr area added to the structural damage, bringing the castle buildings close to collapse. Only radical restoration measures from 1974 to 1989 saved the late Gothic castle complex from total decline. Today it is used as a venue for concerts, cultural events and festivities. It also houses a café. The castle's park is popular for walking, picknicking, jogging and biking.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.