The Roman Catholic parish church of St. Alban in Diedorf, dedicated to St. Alban of Mainz, is a neo-Gothic hall church with a gabled roof. The building with five window axes made of ashlar masonry has a recessed choir in the east with an apse closed on three sides. The bell tower in the west has a pointed spire.

The neo-Gothic altars are by Anton Becke from Wiedenbrück. In the choir there is a winged altar with reliefs about the life of Christ, the side altars are dedicated to Mary and Joseph. The windows in the choir show figurative motifs.

In a niche on the north wall of the church is a Holy Sepulchre with eight sandstone statues that were painted in color at the end of the 19th century. The exact origin of this remarkable group of sculptures is not known. It probably stood in a St. Egidien church in the Eisenach region and came to the southern Eichsfeld region after the turmoil of the Peasants' War. It may also have been intended for the unfinished pilgrimage church in neighboring Katharinenberg. It was then placed in the Diedorf church.

The parish of St. Alban belongs to the deanery of Dingelstädt in the diocese of Erfurt.