The home of the Danish Crown Jewels and Royal Regalia. Rosenborg Castle is a renaissance castle, and was originally built as a country summerhouse in 1606. It is an example of Christian IV's many architectural projects. It was built in the Dutch Renaissance style, typical of Danish buildings during this period, and has been expanded several times, finally evolving into its present condition by the year 1624. Architects Bertel Lange and Hans van Steenwinckel the Younger are associated with the structural planning of the castle. The castle is open to the public for tours and houses a museum exhibiting the Royal Collections, artifacts spanning a breadth of royal Danish culture, from the late 16th century of Christian IV to the 19th century. Some of these articles once belonged to the nobility and the aristocracy. The castle, now state property, was opened to the public in 1838. Of special interest to tourists is a treasury displaying the Crown Jewels and the Danish Crown Regalia located in the castle. A Coronation Carpet is also stored there. The Throne Chair of Denmark is located in the castle. In the summer time, flowers bloom in front of the castle in the castle garden.