English Heritage have marked the position of Stone Hole 97 with a very handsome marker.
Stone hole 97 was discovered by Mike Pitts in 1979 and is alongside the Heel Stone, it may be where a companion stone to the Heel Stone stood, or where the Heel Stone was moved from. The centre of it is abut 2m from the nearest point of the heel stone and is "cut through by the ditch around the Heelstone", with it mainly lying within the ditch enclosure.
Unfortunately the marker is about 5m from the Heel Stone and entirely without the ditch enclosure. If it marks where the second of a pair of stone stood the effect of two pillars bracketing the solstitial sunrise is now not obvious.
Before the marker was installed I wrote a bog post about getting the position correct. :(
ORIGINAL POST from May 2013
One of the improvements that is planned for Stonehenge is the marking of Stone Hole 97 and the Solstitial Alignment on the ground. But the plans seem to have 97 marked in the wrong place.
UPDATE - EH say the mistake has been noted and will be corrected.
April 2012 EH plans for after the A344 is closed and grassed over from http://southplanning.wiltshire.gov.uk/public-planning-application-documents/00543000/00542853_Amended_Plan.pdf
Mike Pitts' plan at the same orientation taken from:
Mike Pitts' plan (and he discovered Stonehole 97) from http://mikepitts.wordpress.com/2012/12/01/stonehenge-in-five-easy-stages-or-perhaps-six/
A more detailed plan of the Heel Stone area, though I haven't located the original source.
Heelstone, Stonehenge - Refraction Seismic (1984) from http://www.panoramio.com/photo/58474363 by Gary Denke
Click any to embiggen