Stonehenge will undergo its first renovation in more than 60 years to fix cracks and holes caused by wind and rain.
Laser scans had detected some erosion in the lintel stones, which are the stones that have laid across the tops of the vertical stones for thousands of years. There is also some damage in the joints and concrete mortar.
Scaffolding will be erected around the prehistoric structure, and the deteriorating concrete mortar that was added to some of the stones in the 1950s will be replaced with a more breathable lime mortar.
In 1958, the stone was repaired using concrete and was lugged back to its place on top of two vertical stones.
Stones 122 and 22 had been the first stones to fall since 1797, when a rapid thaw followed a severe frost.
The new repairs by specialist conservators are expected to take two weeks to be completed.