Baalbek is the Roman sanctuary of Heliopolis in Lebanon’s Beqaa Valley, about 67 km north-east of Beirut and some 1,150 m above sea level, and its podium wall holds three limestone blocks of about 800 tonnes each. Those blocks, known as the Trilithon, and three even larger monoliths still lying in the nearby quarry are why Baalbek is spoken of as an engineering puzzle. Above them stand the six surviving columns of the Temple of Jupiter, at 19.9 m the tallest of any classical temple, and beside them the Temple of Bacchus, one of the best-preserved Roman temples anywhere. The sanctuary grew over roughly three centuries from the reign of Augustus, later served as an Arab fortress, and joined UNESCO’s World Heritage List in 1984.
The Trilithon and the Quarry Monoliths: Weighing the Stones
The Temple of Jupiter rises from a platform built over an earlier T-shaped base. Its lowest courses use about 24 monoliths of roughly 300 tonnes each. On the west side, a second course holds the three blocks that have been called the Trilithon, or Three Stones, since at least the early Byzantine period. Each is about 19 m long, 4.2 m high and 3.6 m thick, and weighs an estimated 750 to 800 tonnes; they are among the heaviest blocks ever used in a building.
The quarry that supplied them lies roughly 800 to 900 m from the temples and slightly higher than the sanctuary, which meant the stones never had to be lifted uphill. They may have been moved on rollers along temporary earthen banks, but the exact technique has never been demonstrated. Three monoliths that never left the quarry show how far the builders were prepared to go:
- Stone of the Pregnant Woman (Hajar al-Hibla), the First Monolith: about 20.5 m long and 4.2 m high, estimated at 1,000 tonnes by a team from Linz, Austria, that surveyed it in 1996. It lies at an angle, still joined to the bedrock at its base, and a 2015 study found cracks and a defect on one face that may explain why it was abandoned.
- Stone of the South (Hajar al-Guble), the Second Monolith: rediscovered in the 1990s and estimated at 1,242 tonnes.
- Forgotten Stone, the Third Monolith: found by the German Archaeological Institute in 2014, with weight estimates of roughly 1,500 to 1,650 tonnes, the heaviest of the three.
Local stories explain the first monolith’s name in different ways: a pregnant woman who promised to reveal how to move the stone if the townspeople fed her until she gave birth, pregnant jinn set to quarry it, or a belief that touching it brings fertility. None of the quarry blocks was ever used, and they are believed to have been meant for the Jupiter complex, possibly as an extension of the Trilithon.
The Temple of Jupiter Heliopolitanus and Its Six Columns
On top of that platform the Romans built the largest temple to Jupiter in their empire. Work probably began soon after about 16 BC, when the town became the Roman colony of Colonia Julia Augusta Felix Heliopolitana, probably settled by veterans of the 5th and 8th Legions, and a graffito on a top column drum shows it was largely finished by around AD 60. The temple measured about 88 by 44 m and was surrounded by 54 unfluted Corinthian columns, ten at each end and nineteen along each side. Each shaft was 19.9 m high and nearly 2.5 m across, and the peak of the pediment is estimated to have stood 44 m above the courtyard. Architrave and frieze blocks weighing up to 60 tonnes, with one corner block over 100 tonnes, were raised 19 m off the ground.
The god worshipped there was a local one in Roman dress. Baʿal Haddu, the Semitic storm god, was equated first with the Greek sun god Helios and then with Zeus or Jupiter, and his cult image was a beardless golden figure holding a whip, a thunderbolt and ears of grain. The sanctuary had an oracle; the emperor Trajan consulted it twice, the second time about his war against Parthia. Nero added a tower-altar opposite the temple in the mid-1st century, and Trajan a forecourt with porticoes of pink granite shipped from Aswan in Egypt.
What remains is the result of centuries of loss. Earthquakes damaged the temple; it was demolished under Theodosius in 379 to make way for a basilica, and between 532 and 537 eight of its columns were shipped to Constantinople for Justinian’s rebuilt Hagia Sophia. Travellers in the 16th century still counted 27 standing columns. By the eve of the 1759 earthquakes there were nine, and today six stand along the south side with their entablature. Their capitals are almost perfect on the south faces, while the winter winds of the Beqaa have worn the north faces nearly smooth.
Why the Temple of Bacchus Survived Best
Beside the Jupiter platform stands the temple that most visitors photograph. It is 66 m long, 35 m wide and 31 m high, only slightly smaller than its neighbour, and was probably commissioned by Antoninus Pius, emperor from 138 to 161; its ornament dates to the 2nd century AD. Its link with Bacchus was first proposed by the German archaeologist Otto Puchstein from the carvings, including dancing maenads on the interior parapets, and is widely accepted but not certain.
The temple was ringed by 42 unfluted Corinthian columns, eight at each end and fifteen on each side, nearly 20 m tall, and nineteen still stand. Inside, the cella has two levels of niches framed by Corinthian pilasters, a 30 m nave and a raised sanctuary reached by 13 steps. The entablature, with its frieze of alternating bulls and lions, and the carvings of the peristyle are among the most refined Roman reliefs to survive; four small figures in the peristyle have even been identified as mites. One likely reason it fared better than the Temple of Jupiter is that it was protected by rubble from the rest of the site until a German expedition excavated the great temples between 1898 and 1903. The 1759 earthquakes still left their mark: the keystone over the doorway slipped about 1 m, and a rough masonry pier was built under it in the 1860s or 1870s.
From Heliopolis to al-Qala’: Phases of the Site
The hill of Tell Baalbek has been lived on for 8,000 to 9,000 years, watered by the Ras al-Ayn spring and meltwater from the Anti-Lebanon range. In the Canaanite period its temples honoured a triad of Baʿal, Astarte and Adon. After Alexander the Great’s conquest in the 330s BC the town took the Greek name Heliopolis, “City of the Sun”, used under the Seleucids and Ptolemies. The Roman colony followed under Augustus, and the sanctuary grew for some three centuries, eventually holding temples to Jupiter, Venus and Bacchus on the tell and one to Mercury on a nearby hill. It came to rival Praeneste in Italy as one of the two largest sanctuaries in the Western world.
Christian emperors turned on it. Constantine demolished the temple of Venus and built a basilica in its place, Theodosius pulled down Jupiter’s in 379, and the Temple of Bacchus was gutted by fire in 554. Arab armies took the town in the 630s, and the ruined temple platform was fortified as al-Qala’, “the Fortress”. It was sacked by the Umayyad caliph Marwan II in 748, by Byzantine forces in 974, besieged by Zengi in 1139, and later held by Saladin. The Mongol general Kitbuqa took it in 1260 and pulled down its defences; most of the fortifications seen today date from the rebuilding ordered by the Mamluk sultan Qalawun in the 1280s. In Islamic legend the complex was a palace that jinn built for Solomon as a wedding gift to the Queen of Sheba, and the medieval walls hid its Roman origin from visitors as late as the 16th century. Earthquakes in 1139, 1157, 1170 and 1759 did further damage. Modern study began in 1898, the year Kaiser Wilhelm II passed through on 1 November, when a German expedition started five years of excavation.
Baalbek Since 1984: Festival, Heritage Listing and Conflict
UNESCO inscribed Baalbek in 1984, describing it as one of the finest examples of imperial Roman architecture at its height. The temples are also a stage: the Baalbeck International Festival, founded in 1955–56 under President Camille Chamoun, holds concerts, opera, theatre and jazz among the ruins each July and August. The modern city of Baalbek, capital of Baalbek-Hermel Governorate, had 82,608 residents in 1998, mostly Shia Muslims along with Sunni Muslims and Christians.
The site’s location has exposed it to Lebanon’s wars. During the 1975–1990 civil war protection of the ruins lapsed, and conservation resumed in the 1990s. The temples suffered minor damage from the shockwaves of nearby Israeli bombing in the 2006 war, after which repair work began that October. Baalbek is a political stronghold of Hezbollah, and since 2023 the area has again been hit by Israeli airstrikes in the Israel–Hezbollah conflict. In 2024 Israel issued displacement warnings for the whole city, and airstrikes shortly afterwards killed 19 people. To place Baalbek in the country around it, read our Lebanon country guide or the profile of Beirut, the capital; for another great Roman-era sanctuary in the Levant, compare it with Palmyra in Syria.