The river Sauer that flows past the town now forms the border between Luxembourg and Germany; in the later Roman Empire and under the Merovingians by contrast, the Sauer did not form a border or march in this area. The Roman villa at Echternach (traces of which were rediscovered in 1975) was reputed to be the largest North of the Alps. It was later part of the Electorate of Trier (present-day Germany) and was presented to Willibrord by Irmina (Irmine), daughter of Dagobert II, king of the Franks.