Altenmarkt an der Triesting is a town in the district of Baden, in the Austrian state of Lower Austria. It lies in the eastern part of the country, within the Triesting valley, from which it takes the second part of its name.
The town is one of several municipalities that make up the Baden district, a region south of Vienna known for its wooded hills and its position on the eastern edge of the Alps. The Triesting river, a tributary of the Leitha, runs through the area and gives the settlement its setting.
As with much of Lower Austria, the town is administered as a single municipality that includes surrounding villages and hamlets alongside its central settlement. Its location in the Triesting valley places it within reach of the wider Vienna metropolitan region while remaining part of a largely rural district.