The Heptastadion was a giant causeway, often referred to as a mole[1] or a dyke built by the people of Alexandria, Egypt during the Ptolemaic period.[2] It connected the island on which the Pharos lighthouse stood to the mainland. It is also believed to have served as an aqueduct while Pharos was inhabited.[3] Due to silting over the years,[1] the former dyke now forms the Mansheya isthmus.[4] Its name comes from its length: seven stadia (Hepta meaning seven).[3]