Stonehenge’s layout holds clues.
Above the trilithons the pattern below, of four equally spaced parallel lines, is where four roof trusses were located, their weight resting on the capping stones. The trusses spanned a central void, a large hall used for gatherings.
The trilithons supported rof trusses – that why they exist!
Logic backs this assertion. Stonehenge’s stones tell us it’s builders were planning something big and magnificent. Why else go to such trouble to shape and shift massive stones, and cap them.
The roof trusses were formed at ground level and raised by pivoting. To do this solid stone was necessary – another reason why hard sarsen stone was chosen. Softer stone would crumble.
The diagram above explains why the trilithons are of different height. Raising four trusses becomes complicated if adjoining pairs of trilithons are the same height.
Though big the roof span at Stonehenge was not impossibly large. Westminster Hall is much wider!