The Belvedere on the Pfingstberg is a palace in the northern part of the New Garden in Potsdam, atop Pfingstberg mountain. It was commissioned by Friedrich Wilhelm IV and is only one part of an originally substantially more extensive building project. The twin-towered building was modeled on of Italian Renaissance architecture, and it was built between 1847 and 1863 with an interruption from 1852 to 1860. From sketches of from the king, the architects Ludwig Persius, Friedrich August Stüler and Ludwig Ferdinand Hessian drew up details plans. The garden architect Peter Joseph Lenné was responsible for the design of the grounds.
The building fell into disrepair, but was repaired between 1988 and 2005 by a group of local residents. Today, the Belvedere is open for tourists.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.