Stonehenge Simply Done
The typical modern mind struggles to build a structure with such heavy stones. With modern cranes, the task of placing twenty tons of stone on top of two pillars is not easy. Without cranes, seemingly impossible.
A major difficulty with the task is the mindset of the viewer.
"How does a person place 20 tons of stone on top of two pillars, each one being about 15 feet high."
Again, like Polya said, the problem is in the mindset. Often mental impediments afflict many a problem solver.
Suppose the problem was "How to put two pillars under a 20 ton stone supported 16 [sic] feet above ground. Now some new ideas percolate into the conscious mind. Name the stone as a Lintel.
Working with 20 tons of stone creates some daunting challenges. If the scaffold breaks, no easy lifting repairs the damage. If the Lintel slips, no first aid heals the wounded. The Lintel is heartless and uncaring.
So, is there another point of view? Yes. Like the Youtube man in Michigan who raises a cross piece on a stack of 4x4's, the builder raises the Lintel and then tilts the pillars under it. Still tricky, but workable with primitive tools.
The Up and Down Algorithm
1) the builder buries a stack of oak beams, pinned together, so that the top is at ground level.
2) the builder slides the middle of the lintel onto the stack.
3) to the left, the builder digs away two feet of dirt.
4) the builder places heavy weights on the left end of the lintel, which causes the left to descend and the right end to ascend.
5) the builder slides 4 inches of oak beam onto right top edge of the stack and under the right middle of the lintel.
6) the builder moves the weights from the left to the right end, which causes the right end to descend and the left to ascend.
7) the builder slides oak beams onto the left top edge of the stack and under the left middle of the lintel.
8) the builder fills in the middle of the stack. Presto! up four inches
This see-saw has raised the lintel 4 inches. Repeating raises the lintel finally to 16 feet. (Repeat steps 4 thru 8 over and over)
9) Tilting a pillar under each end takes some more engineering, but many ancient sites demonstrated the concept.
10) with weights again on the right end, lift left end of the lintel to allow removal of beams from the left edge of the top of stack.
11) remove a few beams.
12) move the weights to the left and lower the right end.
This see-saw lowers the lintel onto the pillars