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.

[1] The Heiligenberg is a low sandstone mountain, with a highest elevation of 439.9 metres (1,443 ft), on the western edge of the Odenwald where it meets the Bergstraße Route and the Upper Rhine Plain.

Archaeological investigations have taken place there several times since 1881, including in the 1920s and 1930s during the building of a guest house and the Nazi-era Thingstätte; finds of Neolithic linear pottery show it was inhabited as early as 5500–5100 BCE.

Celts settled there beginning in the first half of the first millennium BCE and constructed a double-walled hill fort around the primary and secondary peak.

Under the Romans there was a sacred precinct on the mountain: the foundations of a north-orientated temple to Mercury, with an apse, can be seen in the nave of the now ruined medieval basilica of St. Michael.

The Roman shrine was plundered in the Migration Age, but cultic use of the site appears to have continued until approximately 600 CE, since burials were made there until then.

The Heiligenberg has sometimes been identified with the Mons Piri mentioned by Ammianus Marcellinus, where in 369 forces of the Roman Emperor Valentinian I dug trenches but were repulsed by Germanic tribesmen.

The first written mention of the Heiligenberg, as "Aberinesberg", dates to around 870, when abbot Thiotroch of Lorsch Abbey founded a monastery at the site of a former Carolingian royal estate.

In 1090 a monk named Arnold established a shrine on the lower summit, and a second monastery dedicated to St Stephen, a provostship, was founded there in 1094.