The castle of Rosenborg, is a Renaissance castle located in the center of Copenhagen. Ancient royal residence is now home to Danske Kongers Kronologiske Samling, Museum of Royal Danish Collections. The castle was built as a royal residence by the will of King Christian IV of Denmark. The construction site began in 1606 with the real architect Bertel Lange, later modified by his successor Hans van Steenwinckel the Younger the castle is expanded several times in eighteen years. In fact, the last works took place in 1624. The castle was the residence of the royal family until 1720. After the reign of Frederick IV of Denmark, the castle was used as the residence of a royal family only on two occasions, both of an extraordinary emergency . The first time it was in 1794 when the Christiansborg palace burnt down, and the second one during the Battle of Copenhagen in 1801. On the third floor of the castle there is the Sala dei Cavalieri, completed in 1624. It was originally used as a dance hall but around 1700 was used for real receptions, such as banqueting halls. It was only in the mid-1800 that he assumed his name today when he became the Hall of the Throne. Twelve Tapestries of Gobelins, wished by Christian V, depict the real victories in Scania's War on the walls. The barrel vault was coated with stuccoes in the sixteenth century and shows the coats of arms of the Danish Royal House, the Order of the Elephant and the Order of Dannebrog, as well as events of the reign of Christian IV. The castle is open to the public and hosts the Danske Kongers Kronologiske Samling, the Museum of Royal Danish Collections, a collection of artistic artifacts, paintings and tapestries that illustrate the culture and art of the Danish Kings from the 17th to the 19th centuries. It was opened in 1838 and is now owned by the Danish state. Particularly the castle welcomes the precious Danish crown jewels, the Persian rug of crowns, and the royal throne. Generally, every year 2,5 million visitors from all over the world come to visit the castle. The castle stands in the center of the beautiful Renaissance gardens, the oldest royal gardens in Denmark. They were created according to the wishes of Christian IV according to the Italian garden scheme. Today partly transformed into English park, they are open in the summer and represent a real attraction. They have become famous for the spring bloom of Crochi, which are arranged in geometric designs, forming a characteristic color rug.