The Roman temple complex in Lebanon famous for some of the largest stone blocks ever used is Baalbek.
Known in antiquity as Heliopolis, Baalbek developed into a monumental Roman sanctuary from the late 1st century BCE through the Roman imperial period. Its principal temples honored Jupiter, Venus, and Bacchus, and the complex became one of the grandest religious sites in the Roman world.
The site’s most spectacular engineering feature is the massive limestone podium of the Temple of Jupiter. Three blocks known as the Trilithon are each more than 19 metres long and are commonly estimated to weigh about 750–800 tonnes. Nearby quarries contain even larger unfinished stones, including the Stone of the Pregnant Woman and the Stone of the South.
Baalbek is sometimes mistaken for a single temple, but the name refers to the broader archaeological site and ancient city. The Temple of Jupiter is only one part of the complex; the Temple of Bacchus is also remarkably well preserved. The sanctuary was later damaged by earthquakes, reuse of its stone, and religious and political changes.