The Temple of Jupiter is a colossal Roman temple, the largest of the Roman world, situated at the Baalbek complex in Heliopolis Syriaca. The temple served as an oracle and was dedicated to Jupiter Heliopolitanus.
It is not known who commissioned or designed the temple, nor exactly when it was constructed. Work probably began around 16 BC and was nearly complete by about AD 60. It is situated at the western end of the Great Court of Roman Heliopolis, on a broad platform of stone raised another 7 m above the huge stones of the foundation, three of which are among the heaviest blocks ever used in a construction. Cultic activity had long taken place at the site; the temple presumably replaced an earlier one, possibly using the same foundation.
It was the biggest temple dedicated to Jupiter in all the Roman empire. The columns were 19.9 meters high with a diameter of nearly 2.5 meters: the biggest in the classical world. It took three centuries to create this colossal temple complex.