Dirt ramp. Pile dirt up all around the posts. When you have enough dirt, drag your lintel up the ramp, place it, repeat for all posts. Now, everyone grabs a basket and digs away until you have nothing but your new Stonehenge. Smooth out the site, put in your chalk holes to count the eclipses, erect your sighting stone along the line for the solstice and finish up the rest of the landscape. (Oak trees and mistletoe!) Finally have a dedication ceremony, hopefully without human sacrifice, and drinks all around.
“Pile up the Dirt”
Very good suggestion.
The only slight snag is there is almost no dirt on that plateau, the grass only just holds on to life.
:)