Oberkirche, Gothic church ruins in Bad Frankenhausen, Germany

The Oberkirche is a ruined Gothic church whose square masonry tower rises above the surviving stone walls. The tower has a clock face, a dark curved roof, and an octagonal lantern with a small domed cupola. Its top leans about 4.6 metres from the vertical, the largest overhang of any German church tower.

The church was completed in 1382 and suffered severe damage during the Peasants' War in 1525 through violent conflict. Subsequent conflicts over the centuries left additional marks on the building's structure.

The church is a ruin closed since 1908, so there are no services or visitor observations to make inside. Its name links it to the Brotherhood of Corporis Christi, which had it built on Romanesque foundations; the last Catholic service was held in 1539, after which the first Protestant clergyman was appointed.

The church was closed in 1908 for safety reasons and has been a ruin since; the tower leans 4.6 metres from the vertical. Two 11-metre sandstone buttresses were added at the north-east corner in 1911 to slow the tilt. The site is a heritage monument, so expect uneven ground and no visitor facilities.

The tower leans 4.6 metres off the vertical, a greater overhang than the Leaning Tower of Pisa, which measured 3.97 degrees in 2011. Gypsum and salt leaching in the subsoil caused the tilt, which accelerated after a ground collapse 500 metres away in 1908. Two 11-metre sandstone buttresses added in 1911 pressed on the ground and sank faster than the tower itself.