Baalbek is a Phoenician city in the Beqaa Valley at the foot of the Anti-Lebanon Mountains. Although inhabited since prehistoric times, Baalbek did not reach its pinnacle until the Roman era, when it became an important place of pilgrimmage. Baalbek came under Roman control during the Roman expansion to the east at the end of the Hellenistic period, when new settlers installed a colony, Colonia Julia Augusta Felix Heliopolitana. This colony may have been comprised of the veterans of the 5th and 8th legions under Augustus. The temples of Baalbek were constructed over more than two centuries and now represent one of the best examples of Imperial architecture.
Baalbek soon became one of the most renowned sanctuaries of the Roman world as pilgrims visited the city to venerate Jupiter, Venus and Mercury. These deities were referred to as the Romanized Triad of Heliopolis and were a Phoenician cult that was adopted by and adapted to Roman rule.
The main sites in the sanctuary are the temples of Jupiter, Bacchus, Venus and Mercury, plus the Odeon. The temple of Heliopitan Jupiter was the main cult site of the Triad of Heliopolis and replaced an earlier temple. The building works took around one hundred years; started in the mid-1st century BC they were not finished until AD 60. The temple had a monumental appearance thanks to its 20 m high columns surrounding the cella and a terrace made out of huge stones. Sadly, the temple was heavily damaged by earthquakes in late antiquity and was eventually demolished in A 379 under Theodosius. By the 2nd century AD the complex also had a round temple (tholos) to Venus and an exceptional temple to Bacchus. The latter had a conspicuously decorated appearance with Bacchic figures, most impressively those on its monumental gate. Finally, the temple of Mercury had a stairway carved from the rock. This sanctuary is one of the most outstanding of the Roman apogee, and clearly reflects the wealth and power of the empire and the way its representatives decided to advertise Roman power.
The site has managed to remain intact despite the armed conflict that brought an unplanned development in the area. Both national and international bodies have contributed to the preservation of the site. However, the sanctuary complex is still a very vulnerable area and so a protection plan is under preparation in order to improve its preservation and presentation.