The Shrine of Jupiter is in the eastern part of the area in front of the Four Small Temples (II,VIII,2). It is directly to the south of nymphaeum II,VIII,3, and like the nymphaeum was excavated in 1913.

The shrine has been dated to the late first century BC (opus reticulatum). It consists of a square room (4.88 x 4.95), with door-posts and a threshold of travertine. Four travertine cippi (0.77 x 0.24) were found in the four corners of the room, embedded in the masonry. They carry the inscription:

The cippi are boundary stones of an area, and suggest that the structure did not have a roof. The cippi are not easily explained. Perhaps they were collected here after the reorganization of a plot of land, perhaps a bolt of lightning was ritually buried here ...