This mural, above the altar in the lower prison, depicts Peter baptizing his jailers using the spring water found in the prison.
According to historical sources, high-status prisoners were detained here from the sixth century B.C. on—including captive kings and rulers. According to Christian tradition, this is where Peter and Paul were kept—at different times, probably while awaiting execution. Of course, Acts 28:30 indicates that Paul spent two "full years in his own rented quarters" (NASB).