Grotto seer of Lilybaeum, also called Grotto of Sibyl, located directly under the church of San Giovanni Battista, built in 1555 by the Jesuits monks at Cape Capo Boeo. Tradition links the crypt with the name Sibyl Cumana, known also as Sybil Sicula. Sybil (or Sibyl) were called in ancient times Sibyl future, clairvoyants.

Church of San Giovanni Battista was not the first erected on this spot - on the contrary, together with the church of Santa Maria della Grotta it was part of the ancient abbey Padre Baziliani.

Sybil Grotto is located at a depth of about 5 meters under the ground and consists of a central circular recess associated with two rooms - one is oriented to the north, the second to the west. Niche, embossed directly into the rock, is covered with a kind of low dome of the rock in which the skylight is made - it is connected to a higher floor of the church. There you can see the square vat, not too deep for storing water. North room is also stamped in the rock has the shape of a semicircle. At the level of the floor has a spring that fills the square vat. Before this room features a large stone altar with carved image of St. John the Baptist (Giovanni Battista in Italian). The altar, dated to the 15th century, is of great value. West room of irregular shape, was probably built in part from the well.

Given the existence of the cave spring and proximity to the sea, the people born the legend that it is here Ulysses came to quench their thirst. It is also said that in this very cave lived Sibilla Cumana - one of the most famous ancient prophetesses. Near the grotto is a kind of bed that seems carved in the rock - according to legend, it was resting and Sybil.