Book Review of Shimon Gibson's 'The Cave of John the Baptist' from Archeaology Magazine, November/December 2004.
Suba Cave is west of Jerusalem just outside the village of Ein Kerem, possibly John's birthplace. The cave was excavated in 1999 and 2000. Earliest occupation was probably between 800 and 500 B.C. Inside there is a reservoir proposed to have been used for baptism rituals.
Primitive drawings indicate that the cave was periodically used by early Byzantine monks who may have associated with John. There is an early Byzantine depiction of the saint, probably dating to before the sixth century and could be the earliest ever discovered.
-Article by Sandra Scham, editor of Near Eastern Archaeology
more info: http://www.tfba.org/projects.php?projectid=3