These horrible creatures from ancient times have been located on the great religious temples in Europe. Their best times were during the Gothic style and certainly the most famous are those of the cathedral of Notre Dame of Paris. Its horrible faces not only frightened those who wanted steal in the temples but also were an instrument to reduce the water from the roofs of large buildings in case of heavy rain through their big mouthes. these myths still remain on high, and we can see them in many old buildings, especially in the Gothics ones.
Picture taken in Montmatre - París (Church of "Sacre Cor")