The Romanesque basilica of St Michael in Altenstadt, about 3 kilometres west of Schongau on the road toward the Lech, is the most important historical monument in the area and easily reached by bicycle or a short drive. Built around 1200 on the site of an earlier church, St Michael's has survived remarkably intact — its three-aisled interior with rounded arches and heavy stone columns is essentially unchanged from the medieval period.
The church contains several outstanding pieces of Romanesque art, including the large sculpted crucifix known as the "Great God of Altenstadt" (der Große Gott von Altenstadt), a carved capital depicting Samson, and a number of grave slabs and altarpieces accumulated over eight centuries of continuous worship. The basilica is on the Romantic Road and receives a steady stream of visitors but rarely feels crowded. Entry is free.