The Aftersteg district is located on the connecting road between Todtnau and Notschrei. St. Anna is located in the northern part of the village at an altitude of 781 meters. The church building consists of a 13.95 x 6.35 meter rectangular building with a hipped roof and a 17.35 meter high tower with a pitched roof attached to the east. The dimensions of the nave correspond more to a small chapel. It is the smallest church in the district of Lörrach with a separate bell tower, which is also the lowest. Both the tower and the nave have protruding natural stones in the base area on the otherwise light-colored plastered facade, which continue at the edges as corner ashlars.
In the choir there is a valuable rococo altar from the mid-18th century. This was probably reworked from an original baroque altar by the Schönau carver Franz Joseph Beckert. The altar contains three figures: in the middle stands Mary with the baby Jesus above a blue canopy, on the sides are figures of St. Nicholas and St. Wendelin.