The Heiligenberg is a large wooded hill overlooking the town of Heidelberg in Baden-Württemberg, Germany. It rises to around 440 meters NHN (short for normalhöhennull or standard elevation zero, the equivalent of sea level in Germany). It has been the site of many historic and pre-historic constructions, including a Celtic hilltop fortification, a Roman sacred precinct, several medieval monasteries, modern lookout towers and the Heidelberg Thingstätte, built by the Nazis in the 1930s.