The Valkhof is a hill with a small park. There is the Barbarossa ruin and the St. Nicholas Chapel. The Nikolauskapelle is one of originally two chapels of the Nimweger castle Valkhof. It is one of the oldest buildings in the Netherlands.
The construction of the chapel of St. Nicholas on the Valkhof of the Nimweger Kaiserpfalz, built by Charlemagne, was probably commissioned by Emperor Konrad II in 1030. From the oldest building stock but only parts remain.
The octagonal central space, which encloses a sixteen-cornered handling, is clearly oriented towards the Palatine Chapel in Aachen. The Carolingian model has long led to the Nimweger Nikolauskapelle was predated. It is the only surviving Romanesque central building in the Netherlands.
In 1047 the Valkhof complex was completely destroyed by fire. Only under Frederick Barbarossa, the chapel was rebuilt in 1155 in the old form. After another undated massive destruction, a second reconstruction was added in the late 14th century. Source: Wikipedia
On the Valkhof grounds are also the remains (choir capsis) of the former 12th-century Martinskapelle. It is popularly referred to as Barbarossa-ruïne.