The term grotto was applied to a cave or cavern made by hollowing out the ground, as at the Woodlands, or digging into a bank or hillside, as at Lemon Hill and Monticello. While some grottos were formed out of a naturally occurring cavity or depression—as in the case of the grotto at Belfield—they could also be created artificially, complete with contiguous artificial rockwork [Fig. 1] or constructed simply as a stone summerhouse. They could also be made from a combination of natural and artificial elements. In 1771, for example, Thomas Jefferson described building up a natural cave with rock or clay, then covering it with moss or thatch.
A general characteristic of the grotto was its ornamentation or embellishment with shells, rocks, and bits of glass or, as Richard Stockton wrote in 1767, curious “antiquities.” His wife, Annis Boudinot Stockton, planned her shell grotto at Morven, near Princeton, as a museum for the display of such ancient relics. Not only did Stockton visit Alexander Pope’s garden in Twickenham, near London, which was well known for its extensive shell-covered interior, but he also collected several souvenirs, including a piece of Roman brick from Dover Castle, a piece of wood from the King’s Coronation chair, and other curiosities for this grotto.1