Upper Castle on top of a high hill. The castle was laid out on a triangular ground plan and had three towers at its corners. In the 14th century, at the time of the Angevin kings of Hungary, the castle became a royal residence and was enlarged with a new curtain wall and palace buildings. Around 1400 King Sigismund had a third curtain wall constructed and enlarged the palace buildings. At the end of the 15th century, King Matthias Corvinus had the interior renovated. The Upper Castle also served for the safekeeping of the Hungarian royal insignia between the 14th century and 1526. In 1544 Visegrád was occupied by the Ottoman Empire, and, apart from a short period in 1595–1605, it remained in Turkish hands until 1685. The castle was seriously damaged by the Turks and was never used afterwards. The castle is now open to the public to visit. Lower Castle The Lower Castle is the part of the fortification system that connects the Upper Castle with the Danube. In its centre rises the Solomon Tower, a large, hexagonal residential tower dating from the 13th century. In the 14th century, new curtain walls were built around the tower. During a Turkish raid in 1544, the southern part of the tower collapsed. Its renovation began only in the 1870s and was finished in the 1960s. At present, the Tower houses exhibitions installed by the King Matthias Museum (Mátyás Király Múzeum) of Visegrád. The exhibitions present the reconstructed Gothic fountains from the Royal Palace, Renaissance sculpture in Visegrád, and the history of Visegrád. Royal Palace The first royal house on this site was built by King Charles I of Hungary after 1325. In the second half of the 14th century, this was enlarged into a palace by his son, King Louis I of Hungary. In the last third of the 14th century, King Louis and his successor Sigismund of Luxembourg had the majority of the earlier buildings dismantled and created a new, sumptuous palace complex, the extensive ruins of which are still visible today. The palace complex was laid out on a square ground plan measuring 123 x 123 m. A garden adjoined to it from the north and a Franciscan friary, founded by King Sigismund in 1424, from the south. In the time of Louis I and Sigismund, the palace was the official residence of the kings of Hungary until