The Kavilda stronghold (Kawelecht) was, according to Leonhard von Stryk, first built in 1354 by Bartholomäus von Tiesenhausen. Other sources say it was built in 1361 by Arnold von Vietinghoff, the Master of Livonian Order. The castle was destroyed during the Livonian War somewhere between 1564 and 1582. It was probably knocked down before the invasion of the Poles. Thereinafter Kavilda excisted only as a manor but not as a castle.
The castel was a castellum-like building with a tower-shaped residential building. Nowadays only one and a half floors have remained, most of it under the ground.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.