The Conca del Salto is a gorge and waterfall about 4km from Modica that used to have a number of water mills – there were 13 in all in the Fiumara which runs from Modica to Scicli.  It also is known for a grotto behind the waterfall which attracts speliologists from all over Sicily, and it was this idea that was behind the presepe.  That and having running water!