A disturbing, inexplicable fact, for which no one has ever given an explanation, is that to reach the church of San Luca you have to walk a long portico, about three kilometres long and pass under 666 arches. It starts at Porta Saragozza and goes up the Colle della Guardia to the sanctuary of San Luca. A very strange number, 666, which would seem suitable for anything but a place of worship.