On top of Agoraios Kolonos hill, which is delimiting the Ancient Agora of Athens to the west, stands the temple of Hephaestus, broadly known as ?Thisio?. It is one of the best preserved ancient temples, partly because it was transformed into a Christian church. According to the traveller and geographer Pausanias (1, 14, 5-6), two deities were jointly worshipped in the temple: god Hephaestus, protector of all metallurgists, and goddess Athena Ergani, protecting all potters and the cottage industries. The identification of this temple as ?Hephaesteion? (location of worship of the god Hephaestus) was ascertained by the excavations and investigations that brought to light metallurgy workshops on the wider area of the hill, thus outshining earlier opinions presuming that Theseus, Hercules or Aris (Mars) were the deities worshipped there. The temple was probably erected between 460 and 420 BC by a yet unknown architect, to whom, however, are attributed other temples of similar structure in the Attica region.

The temple disposed of a pronaos (anteroom) and an opisthodomos (back section), both distyle (two-columned) in antis. On the exterior it was surrounded by a Doric colonnade having six columns on the narrow sides and thirteen columns on the longer sides. The entire building, from the crepis (stone base) to the roof, was made of marble produced in the quarries of Pendeli mountain (in Attica), while the architectural sculptures that adorned the temple were of marble produced in the quarries on the island of Paros. On the interior of the cella (in Greek sek?s) was a two-part colonnade forming the letter Π and at the far end was a pedestal, that supported the bronze ceremonial statues of Hephaestus and Athena, created by the sculptor Alkamenis; according to the traveller and geographer Pausanias, they were probably executed between 421 and 415 BC. The lavish sculptural decoration of the temple featured highly interesting metopes that adorned the east and the west side of the external colonnade. The east side numbered ten metopes that were visible from the Agora: they depicted nine of the feats of Hercules. Furthermore, on the north and the south side are depicted four of the feats of Theseus, which probably were the reason why the people named this temple ?Thision?. The frieze does not run across all four sides of the cella, but only the across the pronaos and the opisthodomos. The pronaos features the victorious struggle of Theseus against the claimers of the throne, who were the fifty sons of Pallas; six gods also participate into the fight. The opisthodomos depicts the fight of the Centaurs narrated on the wall which is against the cella. Notable sculptural representations also adorned the pediments of the temple. The west pediment depicted the fight of the Centaurs and the east pediment the reception of Hercules on mount Olympus or the birth of goddess Athena. Several among these sculptures inspired statues that were found in the surroundings of the temple, such as the fragmented and partially preserved complex of two feminine figures, one of which transports the other on her shoulders, as if trying to save her life, (?Ephedrismos? = carrying on one's back), Museum of the Ancient Agora, no of finding S 429), or the trunk of a dressed feminine figure where the movement is intensely underlined; the latter could be one of the acroteria (ornamental corner pieces) of the temple (?Nereis? = water deity, Museum of the Ancient Agora, no of finding S 182).

During the Hellenistic period, bushes or small trees in parallel order were planted into flowerpots around the temple; these pots came to light during excavation. In the seventh century AD, the temple was conversed into a church dedicated to St. George Akamas, and thus stayed in use until the liberation of Greece from the Turkish occupation. During the eighteenth century, many eminent Protestants, who died in Athens, were interred in the edifice, while in 1834 it hosted the ceremony of the first reception of king Otto. Hence the temple was used as an archaeological museum, until 1930, when the American School for Classical Studies in Athens started excavations in the Ancient Agora.