The Collaborative International Dictionary of English v.0.48:

grotto \grot"to\ (gr[o^]t"t[-o]), n.; pl. Grottoes
   (gr[o^]t"t[=o]z). [Formerly grotta, fr. It. grotta, LL.
   grupta, fr. L. crypta a concealed subterranean passage,
   vault, cavern, Gr. kry`pth, fr. krypto`s concealed, fr.
   kry`ptein to conceal. Cf. Grot, Crypt.]
   A natural covered opening in the earth; a cave; also, an
   artificial recess, cave, or cavernlike apartment.
   [1913 Webster]

U.S. Gazetteer Places (2000):

Grottoes, VA -- U.S. town in Virginia
   Population (2000):    2114
   Housing Units (2000): 894
   Land area (2000):     1.329205 sq. miles (3.442624 sq. km)
   Water area (2000):    0.000000 sq. miles (0.000000 sq. km)
   Total area (2000):    1.329205 sq. miles (3.442624 sq. km)
   FIPS code:            33488
   Located within:       Virginia (VA), FIPS 51
   Location:             38.267385 N, 78.824868 W
   ZIP Codes (1990):     24441
   Note: some ZIP codes may be omitted esp. for suburbs.
   Headwords:
    Grottoes, VA
    Grottoes