The Temple of Hephaestus (also called Hephaisteion and - incorrectly - Theseion) in Athens is one of the best-preserved ancient Greek temples. It stands on the highest point of the Kolonos Agoraios, the low hill on the west side of the Agora of Athens. The temple dates from the second half of the 5th century BCE.
In the Middle Ages, the temple was incorrectly labelled because of its metopes as the heroon (hero sanctuary) of Theseus where Kimon placed the bones of Theseus in 475 BCE, as they had been found on Skyros. However, the temple can be identified with certainty as the Temple of Hephaistos and Athena on the basis of the description of Pausanias, who writes that there was a temple of Hephaestus over Kerameikos and Stoa Basileios and statue of the goddess Athena stood by.
The temple is called a Doric peripteros. This means that the entire building is surrounded by a row of Doric columns: 6 columns on the short sides (called "hexastyl") and 13 columns on the long sides. The columns surround the cella, the actual sanctuary where the images of the gods have stood. This is preceded by a pronaos ("front house") and behind it is an opisthodomos ("back house"). Both of these have two columns between their sidewalls ("distyl in antis").
The temple is built entirely in marble, Pentelic marble for the building itself and Parian marble for the carved parts.