The Obelisk by William Stukeley
The Obelisk (foreground) is thought to have been the largest standing stone in the Avebury complex; it once stood in the south-east quadrant and was still in one piece (though recumbent) when Stukeley made this engraving in 1723. The Obelisk was subsequently broken up and used for building material. The place where the Obelisk stood is now indicated by a concrete marker placed there by Alexander Keiller during his restoration of parts of Avebury in the 1930s.
See also Moss’ feature here -