The Romans arrived in the year 15 BC under the leadership of Drusus and Tiberius.
Rosenheim station is at the junction of the Munich–Rosenheim, the Rosenheim–Salzburg and the Munich–Innsbruck lines.
The landscape around Rosenheim was formed during the last ice age from the advancement of the Inn Valley Glacier and later from the Rosenheim lake.
The lake existed about 10,000 years ago, covering the whole Inn valley as far as Wasserburg am Inn, about 25 km north of Rosenheim.
Even today in many places around the city the former shoreline can be recognised where the former flat lake bed changes suddenly into relatively steep embankment.
Rosenheim's development can be traced from its location on intersecting major trade routes.