The fountain is in the form of a triumphal arch with three arches. Four columns of coloured marble placed on tall stylobates mark the openings of three niches: in the central one is the colossal statue of Moses. In the side niches are high reliefs illustrating biblical episodes relating to Aaron (left) and Gideon (right). At the base of the niches, water gushes from a mock cliff made of cipolin marble into basins decorated with four lions.