a large stone quarry, intersected in all directions by aqueducts. Some
of them are cut out of the solid tufa, others built in passages cut
through the tufa; some are blocked up with mud deposit, others with
stalactite; some run for a considerable distance, others being broken
in, in extracting the tufa. They present altogether a curious and
interesting study.
_Opposite S. Prisca, in the vineyard of Prince Torlonia, are remains
of the_