Frederiksborg castle is a castle in Hillerød, Denmark. It was built as a royal residence for King Christian IV, and is now known as The Museum of National History. The current building replaced a previous castle erected by Frederick II, and is the largest Renaissance palace in Scandinavia. The palace is located on three small islands in the middle of Palace Lake, (Danish, Slotsø), and is adjoined by a large, baroque formal garden.