In the middle of the Castelvecchio Forest near Caldaro (Kaltern), a piece of church history can be found. It is the ruin of a basilica dating back to the 6th century AD. Two centuries before, Bishop Vigilius of Trent began to proselytise the Val d'Adige valley. Outside the ruins there is a bowl-shaped depression in the rock, probably a burial site or prehistoric sacrificial site, which according to legend served as a sleeping place for St. Vigilius.

The first written mention dates back to 1191: This "Letter of Vigilius" is today kept in the parish archive of Caldaro. The three-aisled St. Peter's Basilica with its semicircular apse reminds of the ancient church buildings of Aquileia and Milan. Originally it was accessible via a medieval stone bridge. In 1782, the church was closed under Emperor Joseph II, and its decay began. Today the St. Peter's Basilica forms the 7th station of the popular Peace Trail (Friedensweg) and is freely accessible: In the lower part of the apse, remains of the "Last Judgement", a fresco by Master Thomas Egnolt from the nearby village of San Paolo (15th century), are still visible.