Ljubljana's hilltop castle affords views over the river and the Old Town's terra-cotta rooftops, spires, and green cupolas. On a clear day, the distant Julian Alps are a dramatic backdrop. The castle walls date from the early 16th century, although the tower was added in the mid-19th century. The surrounding park was landscaped by Plečnik in the 1930s. The castle also houses a virtual museum showcasing Slovenian history through digital technology.