This UNESCO cover from Austria depicts a miniature sheet issued in 2009, celebrating the
Danube Roman Limes. The Danubian Limes, a network of fortifications along the Danube river, protected the borders of the Roman Empire.The Austrian section is 357.5 km long and includes sites at 46 locations. The site is shared with Germany and Slovakia. In 2021, the western segment of the Danube Limes were inscribed on the UNESCO World Heritage List as part of the set of "Frontiers of the Roman Empire" World Heritage Sites.
