This small room, adjacent to Mary's Tomb, is said to be the location of the betrayal and arrest of Jesus.
This says "Gethsemani" I guess because it's adjacent to the garden where Jesus spent his last night in prayer. But this is actually the Grotto of the Apostles.
The altar
These decorations date the Byzantine Period, roughly 400-800 CE
More Byzantine art
A water cistern from the Byzantine period
Jesus on the cross ... and an electric outlet
The sign as you leave.