Built under the reign of Hadrian, this nymphaeum resembles an open scallop shell embedded in the mountain. In its upper section, the monument forms a semicircle comprising 12 niches which housed the statues of the nymphs. In the centre, a larger thirteenth niche formed the temple itself, in which a statue of the fountain's protective divinity was kept. From the terrace - formerly enclosed by a double portico - steps lead down to a water settling basin. From the foot of the site visitors can enjoy a fine view of this theatrical setting.