It is a small one-naved building partially dug into the ground located in the very centre of both the modern and the antique city, in the TZUM subway. The church features a semi-cylindrical vault, a hemispherical apse, and a crypt discovered during excavations after the Second World War. The walls are 1 m thick and made from brick and stone.
The church was first mentioned in the 16th century and was constructed at the place of a former Roman religious building. It is today a monument of culture known for its mural paintings from the 14th, 15th, 17th and 19th century depicting biblical scenes.
The church is dedicated to St Petka, an 11th century Bulgarian saint. The Church of Saint Petka acquired its present name due to it being a patron of the saddlers in the Middle Ages, who performed their rituals in the church.
According to one theory, Bulgarian national hero Vasil Levski is buried in the church. The theory was supported by the noted research worker of Levski Nikolay Haytov and to an extent backed by the 1956 excavations that discovered several skeletons in the crypt, as well as by press reports from 1937 retelling the stories of those who carried out the burial. The Bulgarian Academy of Sciences Institute of Archaeology, however, does not support the view, which led to a harsh controversy in the 1980s that did not end with a conclusive decision.