Vianden Castle was built between the 11th and 14th Century on the foundations of a Roman castle and a Carolingian refuge. This Castle-Palace bears the Hohenstaufen characteristics and is one of the largest and finest feudal residences of the Roman and Gothic eras in Europe. Until the early 15th Century it was home to the powerful Counts of Vianden who could boast of their close connections to the German Imperial Court. The greatest of them, Count Henry I (1220 -1250) was even married to a member of the Capetian family, which ruled France at the time. In 1417, the castle and its lands were inherited by the younger line of the German House of Nassau, which -in 1530- also acquired the French principality of Orange. The castle's most remarkable rooms; the chapel as well as the small and the grand palaces were built in the late 12th and the first half of the 13th Century. In 1890 the castle became the property of Grand Duke Adolphe of the elder line of Nassau and remained in the hands of the Grand Ducal family until 1977 when it was transferred into state ownership. It has been painstakingly restored to its former glory and today ranks among the most significant historical monuments of Europe. https://www.visitluxembourg.com/en/place/castle/vianden-castle

The old castle, protected by a moat, was built in four periods. The oldest part of the castle dates from the early 11th century. It was a small square-shaped fortress on a massive rock, surrounded by a wide ditch and a second wall facing the valley. Around the first half of the 12th century, a flanking tower was added and the access gate was moved and enlarged. http://www.visitluxembourg.com/en/place/castle/beaufort-castle