Mõdriku estate (Mödders) was first mentioned in 1470. Over the centuries, it has been the property of various Baltic German families. During the 20th century, it has been used by various schools. The building traces its oldest parts to the 17th century, but has been extensively enlarged and rebuilt both during the 1780's and 1890's.
The manor was the home of several successive generations of the von Kaulbars family, including Russian general and explorer Alexander Kaulbars. An ancestor to him, R. A. von Kaulbars (reputedly a great patriot) put up the column commemorating the French-Russian War of 1812 that is still visible in the manor park.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.