Bergpark Wilhelmshöhe is a landscape park in Kassel, Germany. The area of the park is 2.4 square kilometres, making it the largest European hillside park, and second largest park on a hill slope in the world. Construction of the Bergpark, or "mountain park", began in 1689 at the behest of the Landgraves of Hesse-Kassel and took about 150 years. The park is open to the public today. Since 2013, it has been a UNESCO World Heritage Site.