Bergpark Wilhelmshöhe is a landscape park in Kassel, Germany. The area of the park is 2.4 square kilometers (590 acres), making it the largest European hillside park, and second largest park on a hill slope in the world [citation needed]. Construction of the Bergpark, or "mountain park", started 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.