1000 Schilling Heidentor Carnuntum

Carnuntum served as the capital of the Roman province of Pannonia Superior and, at its peak, housed a garrison of roughly 50,000 soldiers and civilians. The Heidentor — "Heathen Gate" — is a misnomer that stuck; it is almost certainly the remains of a triumphal monument erected under Constantius II around 354 AD, not a gate at all. The site hosted the 308 AD Conference of Carnuntum, where Diocletian convened the warring tetrarchs in a last attempt to stabilize the collapsing four-emperor system.

Austria's millennial commemoration series of 2000 drew on landmark national heritage sites, and Carnuntum — located in Lower Austria near Petronell-Carnuntum — was a natural inclusion given its ongoing archaeological excavations, which had accelerated through the 1990s.