Though the exact location of Gethsemane cannot be determined with certainty, Armenian, Greek, Latin, and Russian churches have accepted an olive grove on the western slope of the Mount of Olives as the authentic site, which was so regarded by the empress Helena, mother of Constantine (the first Christian emperor, early 4th century AD). An ancient tradition also locates the scene of the Gethsemane prayer and betrayal of Jesus at a place now called the Grotto of the Agony, near a bridge that crosses the Kidron Valley. At another possible location, south of this site in a garden containing old olive trees, is a Latin church erected by Franciscan monks on the ruins of a 4th-century church.