The Pool of Bethesda is mentioned in the Gospel of John as the site where Jesus healed the man who had been an invalid for 38 years.
In John 5:1-15, Jesus came to Jerusalem and met a man at the Pool of Bethesda, which is near the Sheep Gate. The man had lain on the ground every day, waiting for the waters of the pool to be stirred so that he could be the first to enter the pool and be healed. He explained to Jesus that he was unable to move fast enough to be the first person in the water, and the Gospel of John says that when Jesus heard this he healed the man immediately.
The description of the Pool as having five sides, an unheard-of design, led scholars to believe that the story was fiction. However, when archaeologists unearthed this site in the late 19th century, they discovered a Jewish ritual bath, a mikveh, that did indeed have five sides! The Pool of Bethesda today is an elaborate complex marked by Byzantine and Crusader churches. Read more about this archaeological discovery here.