The Château de Beaumont-sur-Oise is an ancient castle, one of the most important in the valley of the Oise. It has a rectangular Romanesque keep with buttresses 25m high and 5m wide. It was probably built by the count Mathieu (1090-1151) to replace a preceding timber structure of the castrum type which had existed from the 3rd century on this rocky outcrop. It was destroyed and rebuilt several times between the 10th and 17th centuries and was no more than a ruin by the 19th century.
The town was developed and built around the castle, with construction in the 10th century of the castle's collegiate church and of a parish church. In 1226, Louis XI became Count of Beaumont and lived in the castle.
The Hundred Years' War and the Wars of Religion were the reason for construction of the upper part of the walls and the keep. The English occupied the town for forty years and the castle itself between 1420 and 1435, when the French artillery of Henri IV caused major damage to the towers of the fortress.
At the time of the French Revolution, the castle was destroyed and then sold off as a national asset. Archaeological excavations carried out from 1984 have revealed the existence of an 11th-century monastery. The castle is owned by the commune.
Trenčín Castle is relatively large renovated castle, towering on a steep limestone cliff directly above the city of Trenčín. It is a dominant feature not only of Trenčín, but also of the entire Považie region. The castle is a national monument.
History of the castle cliff dates back to the Roman Empire, what is proved by the inscription on the castle cliff proclaiming the victory of Roman legion against Germans in the year 179.
Today’s castle was probably built on the hill-fort. The first proven building on the hill was the Great Moravian rotunda from the 9th century and later there was a stone residential tower, which served to protect the Kingdom of Hungary and the western border. In the late 13th century the castle became a property of Palatine Matúš Csák, who became Mr. of Váh and Tatras.
Matúš Csák of Trenčín built a tower, still known as Matthew’s, which is a dominant determinant of the whole building.