The foundation of the former 3-nave Romanesque basilica is expected to be in the middle of the 11th century. Over several construction stages, the church developed to its present appearance. The oldest frescoes, the former pilgrimage church, date from 1250 - 1280. The bells of the church are from 1446 and 1487.
A total of 3 churches were built over 1000 years. Of these, two departed churches have been rediscovered by archaeological investigations.
The oldest of these, about 750 was created as a Carolingian hall church. Unexplained, are the two cross channels, which run on the central axis of the nave.
Probably 950 was built in the immediate vicinity, the so-called "Great Basilica" with a total length of 47 meters. The still accessible underground grave church (crypt) is considered one of the earliest, by Baden Württemberg.
After 30 years of excavations, the Kirchenensamble Unterregenbach still counts as an enigmatic research object of the "early medieval archeology". The turbulent church history of Unterregenbach, can be rediscovered during a group tour, - Unterregenbach "From the pilgrimage to the village church idyll".
Visitors can visit the church during the day, either on their own or as part of a group tour.