The Great Mosque of Baalbek stands near the entrance to the Roman ruins and is one of the earliest surviving Islamic monuments in Lebanon. Built during the Umayyad period (7th–8th century), it was constructed largely from recycled Roman material — columns, carved stone blocks, and capitals from the earlier temples were reused throughout the building, giving it a pleasingly composite character.
The mosque is still active and the courtyard is open to respectful visitors outside prayer times. The prayer hall contains columns of different heights and styles, a visible record of the builders working with whatever was at hand. It is a quieter, more contemplative stop than the busy temple complex next door, and the contrast between Islamic and Roman architectural sensibility is worth spending time with.