Choisy Cathedral, otherwise known as the Church of St. Louis and St. Nicholas, was the first cathedral of the diocese of Créteil, from 1966, when the diocese was created, to 1987, when the present Créteil Cathedral was inaugurated.
The church was built by the architect Ange-Jacques Gabriel under commission from Louis XV to provide a suitable place of worship for the court when the king was staying at his newly purchased residence at the Château de Choisy. The first stone was laid, by the king himself, on 4 July 1748, and the church was dedicated in the presence of the king, the court and the Archbishop of Paris on 21 September 1760.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.