Comment says this image is flopped.

The Hephaisteion, popularly though incorrectly known as the 'Theseion', remains the best preserved of all Doric temples. All the columns and the full entablature of its canonical peristyle (6 x 13 columns) survive, as do the walls of the cella up to ceiling level, though the present roof is of later date. The temple is largely of Pentelic marble and dates from the mid-5th century BC, though it may have taken a generation or more to complete. It carries more sculptural decoration than any other Classical temple except for the Parthenon. Excavations around the building uncovered planting pits, indicating that the sanctuary was landscaped with rows of shrubs and bushes. The Hephaisteion was converted into the Christian church of St George in the Kerameikos, probably in the 7th century AD, resulting in the addition of an apse at the east end and the removal of its pronaos columns and door-wall. This conversion also contributed to its unusually fine state of preservation.