The Red Church, The Church of the Holy Virgin, is a Roman building constructed in the 4th century or, at the latest, by the beginning of the 6th century during the reign of Emperor Anastasius I. It originally had a north altar, which resulted from early Christian worship in the original Roman baths, and a Mithraeum, a bath and temple dedicated to the ancient Iranian god Mithras. The church’s floor initially was a pool, which was later incorporated into the church’s floor and baptistery. The original construction was intended for the Roman legionnaires stationed in the area, who built thermal baths for their needs, evidence of which can be found in the pool discovered in the church.
With the spread of the cult of Mithras, a Mithraeum was built at the baths. A trace of this can also be found in the freshwater spring under the church, which has a built-in fountain, the stone of which has been pierced along its entire length, allowing water to flow from its core. This stone references the legend of the God Mithras, who pierced a stone with an arrow, and water flowed from it. A remnant of the Mithraeum that existed here is a wall painting that was not erased even in Christian times, depicting the rebirth of the god Mithras from a red egg.
The Red Church is considered one of the oldest churches in Europe. Immediately after the Ecumenical Council was convened in Serdica in 343, the construction of cult buildings began throughout Thrace, including those designed to preserve the memory of martyrs who died for the affirmation of Christianity. The location of the Red Church was carefully chosen, as it was near an old pagan sanctuary and close to the important Byzantine city of Philippopolis (now Plovdiv) and the most critical roads from Thrace to the White Sea and from Constantinople to Western Europe.
Today’s Red Church initially functioned as a martyrium, a cult building designed to preserve the memory of martyrs who died to affirm Christianity. Later, the church also served as a summer residence for Byzantine nobles. Frescoes were found preserved on the walls. The temple was believed to be known in the past for the healing powers of a Christian martyr who died to establish faith in these lands.
The temple was dedicated to the Holy Virgin and got its name from the typical Roman bricks and pink mortar from which it was built.