Located in the Beqaa Valley, Baalbek is one of the most impressive archaeological sites in the Middle East. Showcasing the might of the Imperial Roman Empire, Heliopolis, as it was formerly known, became prominent under the Phoenicians but it was the Romans who built the most impressive temples of Jupiter, Bacchus, Venus and Mercury. The mammoth task of building these temples and other structures (including a massive raised plaza) began under the reign of Emperor Septimius Severus in 193AD. Subsequent emperors including Nero enriched the city and, at its height, Baalbek was the largest sanctuary in the Roman Empire with pilgrims thronging to the temples to venerate the three deities of Jupiter, Venus and Mercury.