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1610s, from Italian grotta, ultimately from Latin crypta "vault, cavern," from Greek krypte "hidden place" (see crypt). Terminal -o may be from its being spelled that way in many translations of Dante's "Divine Comedy."
natural or artificial cave used as a decorative feature in 18th-century European gardens. Grottoes derived from natural caves were regarded in antiquity as dwelling places of divinities. Grottoes were often constructed from a fanciful arrangement of rocks, shells, bones, broken glass, and other strangely assorted objects and were commonly associated with water (see nymphaeum).