Incredible engineering marvels were required during construction.
It required a lot of creativity to get the stones to stand up straight. The builders eventually chose a technique associated with woodworking rather than brickwork. They used tongue and groove joints to slot the stones together, creating mortice holes and protruding tenons. Timber poles were placed at the back of the pit as a brace support when the hole for the stones was dug. The stone was then placed into place and lifted up with ropes while rubble was stuffed into the pit to keep it in place.