The street in the southwestern corner of the agora leads to the Temple to Serapis. The cult of Serapis was originally Egyptian but passed into Greek and Roman religious life found fertile ground for growth in Ephesus, where this temple was built. Upon first investigation it was thought that this gorgeous monumental work was built for Emperor Claudius (41-54 AD). However, architectural considerations and the presence of certain statues and inscriptions led to the conclusion that it was in fact constructed in the 2nd century for the Egyptian cult of Serapis.

The temple sat on a terrace above the courtyard. Built along prostyle lines, the column capitals found were 1.5 m in diameter, meaning that the columns were as much as 57 tons on weight. The entrance was extremely wide and had a double door. Since the door was metal, it had wheels on the bottom, which a readily visible track in the floor.

Without a doubt the most attractive part of the temple was the façade. It was 15 m. high with 57-ton columns supporting it on either side and had galleries surrounding a entryway courtyard. It is still possible to see the columns and upper parts in front of the temple. The structure was later used as a church. It is easy to see that earthquakes in ancient times did a lot of damage to the temple.