This film was first shown in 1970 and demonstrates the reaction of the archaeological community to Alexander Thom's work, leading to the notion of Megalithic Science. It describes what started as a technically informed hobby activity in Britain, culminating in field work in near Carnac, Brittany, proposed by Nature's editor as a way of seeing if Thom's theories derived from British monuments supported what is to be found in Brittany. The answer was that the same measures and monument designs are found with some variations.

This can be viewed at theBBC Chronicle Archive page alongside many interesting films.