“The beliefs of Stone and Bronze Age Britons were express in constructions that involved quite fabulous amounts of work. The six-mile-long 'cursus', embanked walkway, outside Wimborne in Dorset represented half a million man-hours of labour, carried out by labourers using deer-horn picks and shovels made from the shoulder blades of cattle. The bank at Avebury would have taken a million of hours. As for the time spent hauling stones and dressing them to a flat surface at Stonehenge (and some of these stones are sarsen, which is harder than granite), what can have motivated the masons to keep pounding away with their stone mauls?”
From a piece in the London Reivew of Books (6 November 2014) about paganism in Britain. Pre-literate societies had an awful lot of time on their hands.