The altar in the center of the image is on the east side of the large grotto.
The natural grotto, 57 ft. [17.6 m.] long and 37 ft. [11.4 m.] wide, has been modified throughout the ages. For example, the "stars" that are painted on the ceiling date to the Crusader Period.
For a brief description of The Cave of Gethsemane Click Here.