Roman bridge, St. Dionysen, Oberaich, Roman stone bridge in Oberaich, Austria.

The Roman bridge at St. Dionysen is a single-arched stone bridge built of rubble stones, located in Oberdorf on the road to Sankt Dionysen in the municipality of Bruck an der Mur, Styria. It is a protected monument.

The bridge is first documented in 1454. It probably belonged to a Roman road running from Flavia Solva through the Murtal to Poedicum (Bruck an der Mur) and on to Stiriate (Liezen). Its dating is uncertain: O'Connor listed it as Roman in 1993, citing a 1960s publication, while Galliazzo's 1994 catalogue omits it.

The bridge is a listed monument (Denkmalgeschütztes Objekt) in the Steiermark register. Its name links it to the Roman road from Flavia Solva via Poedicum to Stiriate, and the nearby Badl bridge with a surviving stretch of that road is also protected. Local tradition calls it a Roman bridge, though scholars disagree on its date.

The bridge is accessible year-round for pedestrians and cyclists and is located near Sankt Dionysen. Access is provided through local paths that are easy to find.

The bridge is not listed in Galliazzo's 1994 catalogue of Roman bridges, while O'Connor's 1993 overview includes it citing a 1960s publication. Near Badl, part of the same presumed Roman road and another bridge survive, giving visitors a second structure to compare.