The Grotta dell`Arsenale is a cave on the island of Capri, southern Italy. It may have been used in the time of Roman emperor Tiberius as a depot for naval stores. It measures 4 m long by 3.5 wide by 1.5 m high. Excavations made in 1777 in the shingle, which still covers the floor to a depth of from 1.2-1.5 m, showed evidence of traces in the wal....