| Altenstadt | |
| Image Coa: | Wappen von Altenstadt (Oberbayern).svg |
| Coordinates: | 47.8167°N 62°W |
| Image Plan: | Altenstadt in WM.svg |
| State: | Bayern |
| Region: | Upper Bavaria |
| District: | Weilheim-Schongau |
| Elevation: | 722 |
| Area: | 18.66 |
| Postal Code: | 86972 |
| Area Code: | 08861 |
| Licence: | WM |
| Gemeindeschlüssel: | 09 1 90 111 |
| Website: | www.altenstadt-obb.de |
| Mayor: | Andreas Kögl[1] |
| Leader Term: | 2020 - 26 |
Altenstadt is a municipality in the Weilheim-Schongau district, in Bavaria, Germany.
Altenstadt ("Old Town") is the former Schongau - a large proportion of residents moved in the 13th century only a few kilometers further and founded a new settlement at the River Lech, and took the town's name as well.
A significant sight is the Romanesque basilica minor of St. Michael with remains of medieval wall painting and several examples of Romanesque sculpture.