Other parks in Stuttgart include the historic Botanischer Garten der Universität Hohenheim and Landesarboretum Baden-Württemberg at Castle Hohenheim (which date back to 1776 and are still used to catalog and research plant species), Uhlandshöhe hill (between the city center, Bad Cannstatt and Frauenkopf, and home to Stuttgart observatory), the Weißenburgpark (a five-hectare park in the Bopser area of Stuttgart South which dates back to 1834 and is now home to a 'tea house' and the 'marble room' and offers a relaxing view across the city center), the Birkenkopf a Schuttberg (at 511 meters the highest point in central Stuttgart, where many ruins were laid to commemorate the Second World War), and the Eichenhain park in Sillenbuch (declared a nature reserve in 1958 and home to 200 oak trees, many 300–400 years old).