Cavers from Ancona found a hole in the Frasassi gorge in 1971 and lowered themselves into the Abisso Ancona, a chamber so vast it could swallow Milan Cathedral whole, dome and all. Only a fraction of that abyss opens to the public: a paved, lit route of about a kilometer winds past crystal-clear pools and stalagmites the size of towers, some still growing by a millimeter every few decades.
Near the entrance, the small octagonal church of Santa Maria infra Saxa, rebuilt in the 1820s to a design linked to the architect Giuseppe Valadier, shelters inside a cliff cave, a startling piece of Neoclassical order tucked into raw limestone. Guides keep groups moving at a steady pace, so the visit covers only a fraction of the system even though the cave system beneath the gorge runs for many more kilometers.
