It is a cruciform church with a horseshoe-shaped apse. It has a burial chamber in the north side. There is not enough light inside the church so the visitor might need a flashlight.
West wall; Christ, the judge, flanked by angels, is seated in a mandorla. Below him are the Forty Martyrs of Sebaste in oriental robes and the Twenty-four Elders of the Apocalypse. Below the west wall again, on the left, Day of Reckoning by weighing the Souls, a monster with three heads, and the body of a serpent devouring some of the damned representing the torments of hell. The name of the church derives from this painting. Next to it, on the right, naked women are being assaulted by snakes. One of them is in the coils of eight snakes probably because of her adultery. Another one’s breasts are being gnawed by snakes because she left her children. Others guilty of disobedience and calumny are attacked on the ear and mouth.
To the right of the door of the burial chamber is Entry into Jerusalem. To the left is St. Onesimus.
Apse; Last Supper, Crucifixion.
East wall; At the top is a cross in a halo, on the inclined wall to the left is the Crucifixion (not well preserved) and Visitation. Top of the north face; St. John the Baptist, right hand raised and left hand holding an amulet. Top of the wall, east of the altar; Christ sitting on a rainbow, Christ dressed in red and holding a book surrounded by archangels Michael, Raphael, Gabriel and Uriel.
South wall; Michael and Gabriel on both sides. Below the window is the Dormition, near the cross is the fresco of Constantine and Helena.