The Heidenmauer ('heathen wall') is a circular rampart or ringwork, two and a half kilometres long, which was built by the Celts around 500 BC. The wooden elements of the wall have disappeared over the course of time by rotting away, but the stones have survived. Copious numbers of pottery finds have enabled a very precise dating. Almost all the containers are hand-made, only a few show traces of having been turned; this technology first appeared after ch 500 BC. in the La Tène period. Other finds included iron, long knives as well as querns, pyramidal stones that were stuck point-down in the ground in order to provide the base for the milling of corn. In addition there is also evidence of milk production and iron smelting.
In the 4th century A. D. a small part of the circular rampart as well as the Kriemhildenstuhl below was used by the Romans as a quarry.References:
The Historic Sausage Kitchen of Regensburg (Wurstküche) is notable as perhaps the oldest continuously open public restaurant in the world. In 1135 a building was erected as the construction office for the Regensburg stone bridge. When the bridge was finished in 1146 AD, the building became a restaurant named Garkueche auf dem Kranchen ("cookshop near the crane") as it was situated near the then river port. Dockers, sailors and the staff of the nearby St. Peter cathedral workshop were the regulars for the centuries to come. The present building at this location dates from the 17th century, but archaeological evidence has confirmed the existence of a previous building from the 12th century with about the same dimensions.
Until ca. AD 1800, the specialty was boiled meat, but when the family who currently own the restaurant took over in 1806, charcoal grilled sausages were introduced as the main dish offered. The kitchen still operates today and serves 6,000 sausages to guests daily.