the highly sacred Osireion at Abydos
“Abydos, where is (…) a fountain [a well, the Osireion] which lies at a great depth, so that one descends to it down vaulted galleries made of monoliths of surpassing size and workmanship. There is a canal leading to the place from the great river; and in the neighbourhood of the canal is a grove of Aegyptian acantha, sacred to Apollo. Abydos appears once to have been a great city, second only to Thebes”
[Strabo, Geography XVII, I, 42]