Art is a huge topic in Kassel. Relics from past art shows are found everywhere and continue to enrich the city landscape till today. The city offers a number of other attractions too. Kassel's state orchestra, with its 500-year-old history, is one of the world's oldest musical ensembles. The Ottoneum, Germany's first permanent theater building, is today a natural history museum with a library of trees. And the Fridericianum is Europe's oldest public museum. Kassel is also home to Germany's oldest pedestrian zone, the Treppenstrasse. The Bergpark Wilhelmshöhe is also a unique park landscape. It stretches over an area of 240 hectares and boasts over 500 varieties of wood. Other highlights include the city's emblem - the Hercules monument, and the Wilhelmshöhe palace with its magnificent collection of paintings by old masters.