The Church of Panagia Chalkeon is an 11th-century Byzantine church in the northern Greek city of Thessaloniki.
The church is located at Dikastirion Square, north of the Via Egnatia at the point where it crosses the Aristotelous Avenue, which leads to the Aristotelous Square. The archaeological site of the city's Roman forum is located northeast, while its name, which translates as "the Virgin of the Copper-smiths", derives from its proximity to the area traditionally occupied by the city's coppersmiths.
According to the founder's inscription above the west entrance, the church was built in 1028 by the protospatharios Christopher, katepano of Longobardia, and his wife Maria, son Nikephoros and two daughters, Anna and Katakale. Christopher's tomb was probably located in an arcosolium on the church's northern wall.
The ground plan is that of a classic "cross-in-square-form" typical of Macedonian-period architecture, with four columns and three domes, one central and two over the narthex. The entire building is built of bricks, which gave it the popular nickname "Red Church". The exterior is enlivened with a variety of arches and pilasters, elements which can be traced to Constantinopolitan influence. The use of arches with several setbacks gives the building a "sculpted" appearance. In the interior, most of the carved marble decoration, as well as frescoes from the 11th and 14th centuries have been preserved.
With the conquest of the city in 1430 by the Ottoman Turks, the church was turned into a mosque, named Kazancilar Camii ("Mosque of the Cauldron-Merchants").
Source: wikipedia.org