The Clock Tower (Grazer Schlossberg in German) is located on top of the Schlossberg hill, which is roughly 475m high. At the top of this hill a castle was built finally naming the city of Graz (which derives from the Slovenian word "Gradec" which means "small castle"). The Clock Tower was the only part of the castle that was saved from demolition as ordered by Napoleon in 1809 following the Treaty of Schönbrunn. Since 1839 the Tower and its surroundings have been a public park, designed by Ludwig von Welden. The clock tower has a curious feature, because its needles work differently to most watches.