Alcimoennis (aka Alkimoennis) was a Celtic Oppidum, or hill fort, located on the Michelsberg hill, dominating the peninsula between the Danube and Altmühl rivers in northern Bavaria, Germany, above the modern city of Kelheim. Although the peninsula has been more or less constantly inhabited since 13,000 BCE, the city as the Celts built it was founded around 500 BCE and abandoned again some time before Roman arrival in the area during the 1st century BCE. It is only identified once in historical documentation, namely in the copious works of the Greek geographer Ptolemy, who left us only the name and location of the city. Who exactly inhabited the city is also unclear.