Work on building Haderslev Cathedral began in the mid-13th century. It was originally a large cross-shaped single-naved church built of bricks and granite cubes recycled from an older church. Only the original transept is still standing. The church nave was soon expanded to include three tall naves under one roof. This type of church is called a hall church. The present three-naved choir from 1400 is one of the most beautiful choirs from the Gothic period and has three incredibly tall 16-metre windows that allow the light to flood in. When South Jutland was reunified in 1920, the church was elevated to the status of a cathedral in the newly established Haderslev Diocese.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.