The church of Agioi Anargyroi (the Unmercenary Saints) stands on the steep hillside on the north side of the city of Kastoria. It is a three-aisled basilica with narthex , which initially had a triple vaulted roof dating to the 10^th -11^th century. On the inside the naves are separated by walls punctuated by asymmetric arched openings. The central nave is wider and higher than the other two, ending in a semicircular conch to the east. The conches of the side naves are the same shape but smaller. The church is illuminated by a few double light windows in the upper wall of the central nave - two on each of the long sides, and one in each of the short sides (east and west). The masonry consists of irregular stones alternating with red tiles arranged in patterns (diamonds, suns, trees and dogtooth courses). These are combined with mortar to create an aesthetically pleasing effect.

Agioi Anargyroi is the only church in Kastoria to have sculpture decoration, featuring carved rosettes, crosses, animals and stars in circles. Inside the church there are also sections of the marble templon assembled during restoration work.

The interior is decorated with successive layers of exquisite wall paintings . The scenes in the first layer, dating to around 1000 AD, are mainly visible on parts of the narthex, where earlier interventions brought to light depictions of Saints Basil and Nicholas, Saints Constantine and Helena, and the figure of the deceased Constantine. These representations are characterized by intensely outlined faces, linear characteristics, a limited number of colours for rendering figures and a lack of volume.

The second layer wall paintings date to the second half of the 12^th century. According to inscriptions in various parts of the church and the dedicatory representation in the north nave, they were sponsored by Theodore Lemniotes and his wife Anna Radene, who renovated the church and dedicated it to Agioi Anargyroi (the Unmercenary Saints), calling on them to intercede for their personal health. Information from the founders’ mural and another scene in the south nave reveal that they took monastic vows - Theodore Lemniotes took the name brother Theophilus Lemnos.

The iconographic programme in the second layer features scenes from Dodecaorton and the Passion of Christ in the nave, the Eucharist in the sanctuary, and the lives and martyrdoms of saints in the side naves. Marked differences in style suggest that two artists with differing concepts of art worked in the nave. In the first case the saints are rendered in a hieratic stance, stern of expression, with oval faces, large round eyes and arched eyebrows.

The garments are rich, painted in a variety of colours, with folds that follow the movements of the body. This painter’s depictions are representative of “dynamic Comnenian style” and recall the art in Agios Georgios at Kourbinovo. In contrast, the slightly earlier figures attributed to the second artist are rigid and expressionless, with linear faces and clothing folds. The main figures appear disproportionately larger than the minor ones, and the scenes are almost entirely devoid of any surrounding detail (buildings or landscape). A third artist painted the surfaces of the narthex in the monumental tradition of late Comnenian painting. The exterior murals on the west facade date to the same period. They depict the Supplication, the Apostles, the Unmercenary Saints and St. Nicholas.