This was built in dedication to Serapis, one of the Egyptian gods, in the2nd century AD. Its façade once reached up to 29m including the pedestals and capitals. Three columns out of a total of eight were really colossal, that is they were 15 m high and weighed 50 tons.
Each one was ornamented with three corinthian capitals made from one block of marbles. The fragments of these columns and their capitals can still be seen.