It is home to the Baalbek temple complex which includes two of the largest and grandest Roman temple ruins: the Temple of Bacchus and the Temple of Jupiter.

Baalbek was called Heliopolis during the Roman Empire, a latinisation of the Greek Hēlioúpolis (Ἡλιούπολις) used during the Hellenistic Period, meaning "Sun City" in reference to the solar cult there. The name is attested under the Seleucids and Ptolemies.

Pre-Hellenistic Period
Baalbek’s origins trace back to at least the 3rd millennium BCE, with its early settlements likely established by the Canaanites or Phoenicians. Known in ancient times as Baalbek (meaning "City of Baal"), it served as a center for the worship of the storm god Baal-Hadad, alongside Astarte and other regional deities. Archaeological evidence indicates a sustained religious presence, with rudimentary temples constructed on the site.

Hellenistic Period (323–63 BCE)
Under the influence of the Ptolemies and later the Seleucids, Baalbek became known as Heliopolis, aligning with the Greek pantheon. It was during this era that the fusion of local Semitic deities with Greek gods took shape, transforming Baal into a counterpart of Zeus. The city grew in significance, with rudimentary monumental structures replacing earlier cult sites, laying the groundwork for later developments.

Roman Period (63 BCE–330 CE)
Rome’s annexation of Baalbek marked its golden age. The city, now fully established as Heliopolis, saw the construction of massive temple complexes dedicated to Jupiter, Bacchus, and Venus. These temples, begun during the reign of Augustus and completed under successive emperors, showcased Roman architectural ambition and engineering. The massive scale and intricate detailing of the Temple of Jupiter highlight its centrality as a provincial religious hub. The Roman influence cemented Baalbek’s status as a pilgrimage site, drawing visitors from across the empire.

Byzantine Period (330–636 CE)
With the advent of Christianity in the Byzantine Empire, the pagan temples of Baalbek faced neglect or conversion. The Temple of Venus became a Christian church, while others were stripped of their pagan symbolism. Earthquakes during this period further damaged the structures, and the city's prominence waned as Christian cities elsewhere in the region rose in importance.

Islamic Period (636 CE onwards)
Following the Muslim conquest of the Levant, Baalbek underwent further transformations. The site became part of the Islamic caliphate under the Rashidun and later Umayyad rule. The remnants of the Roman and Byzantine structures were repurposed for military and civic use. The area served as a minor administrative center, but its significance was eclipsed by nearby cities like Damascus and Aleppo. Later, Ottoman rule saw renewed interest in the site for its historical and architectural legacy.

circa 15 BCE

Temple of Jupiter
The Temple of Jupiter was built on the site of a previous settlement dating back to the Neolithic, Bronze and Iron Ages and the Hellenistic period. It consists of a cella built on a 12 meter high podium and a courtyard surrounded by a colonnaded portico. Though previously planned, the monumental entrance (propylaea), the semi-circular forecourt and hexagonal-court were added only later in the course of the second and third century CE. The sanctuary stood on an unusually high podium of 7 meters. Underground galleries (crypto-porticoes) lying underneath served as cool rooms in summer.

circa 15 BCE

Great Court
The great courtyard is at the heart of the Temple of Jupiter. Underneath lies the ancient settlement and most probably an older sanctuary. During the Roman era, all the older remains disappeared under a high podium surrounded on 3 of its sides by a colonnaded portico. Semi-circular and rectangular exedras richly decorated with statues standing in their niches, opened on the portico. During the important religious feasts, various cities built market stands here. Several statues, with votive inscriptions mentioning the names of the donors, were placed on the steps connecting the courtyard and the main sanctuary of the temple.

Of utmost importance for the cult of Jupiter Heliopolitanus were the two high altars, where sacrifices were offered and the two ablution basins. These two architectural elements played an important role in the pre-Roman oriental cult rituals as well.

The importance of the great courtyard for the cult is also clear during the early Christian period, when in the 5th century CE the two altars were demolished and a basilica was constructed in the area. The remains of this basilica were removed in the 20th century CE to investigate the Roman temple.

circa 15 BCE

Hexagonal Court
The hexagonal courtyard, the only example atteted in Roman architecture, was built in the 2nd century CE and is the most recent element of the Jupiter temple. It served as a forecourt to the main, sacred Great Court. Around the central part of this courtyard, a colonnaded portico protected 4 exedrae. Loopholes and covered pathways were aded during the medieval period when the temple was transformed into a citadel.

circa 15 BCE

Propylaea
The monumental staircase leads from the semi-circular forecourt tot he entrance hall of the Roman temple of Jupiter, the propylaea. The entrance plan followed a widespread Roman prototype and consisted of a long rectangular hall with a row of 12 columns flanked left and right by two-story towers. The decoration of the outer facade as well as the richly ornamented column capitals, which were covered with bronze and gold during the 3rd century CE, could be seen from afar and gave the entrance its impressive character.

circa 50 CE

Temple of Muses
The temple of Muses was constructed in the first century CE, while the temple dedicated to Venus was built in the third century CE. The temple of Venus is a relatively well preserved structure, which owes its baroque aspect to its plan, which consists of a round building standing on a horseshoe-shaped podium. The semi-circular niches on the outer facade are surmounted by a concave cornice. This small temple owes its good statue of preservation to the fact that since the middle ages and up to modern times, it served as a church.

circa 150 CE

Temple of Bacchus
The relatively smaller Temple of Bacchus located on the southern flank of the sacred precinct of Baalbek, was most probably dedicated to Bacchus, the Roman wine god. There are no inscriptions to confirm the identity of the worshipped deity or to provide a clue as to the date of the building. The Bacchus temple is one of the best preserved Roman era temples. It survived several earthquakes, religious changes from paganism to Christianity and then Islam as well as its transformation in to a dungeon during the medieval period, without serious damage.

Its rich Corinthian ornaments suggest a date in the late second century CE. Unlike the Jupiter temple, the Bacchus temple was completely finished as planned. A monumental staircase leads to the stone podium on which both the temple and the colonnaded portico that surrounds in stand. The antecella is ornamented with two rows of niches inside whcih statues once stood. Another staircase leads up to the cella, which was separated from the ante-cella by a canoy-like structure because common visitors of the temple were not allowed to look inside the Holy of Holies. On the right side of the cella, there is a crypt where cult vessels were probably stored.

circa 210 CE

Temple of Venus
The temple of Venus was one of the two smaller temples which stood outside the Roman sacred precinct towards the south-east. This separation is due to the fact that during the Roman period this area was separated from the main temple complex by a colonnaded street. This configuration continued even in the medieval Islamic period when the temple complex dedicated to the Roman gods Jupiter and Bacchus was transformed in to a citadel.

circa 1050 CE

Remains of Arab Fortifications
From 11th until 14th century CE, the main temple complex was transformed in to a citadel and served as a military installation.