'According to (a) hypothesis made by Alan Butler and Christopher Knight, the megalithic civilization of Britain and Britanny, France used 366-degree geometry (also called megalithic geometry). This geometry, the origin of which is claimed to date to c. 3,000 BC, would have used a 366-degree circle rather than the 360-degree circle we use today. Alan Butler also asserts that 366-degree geometry has been materialized on the Earth by what he terms Salt Lines – 366 meridians and 183 parallels crisscrossing the globe at regular intervals (the equivalents of modern-day 360 meridians and 180 parallels).

Most of the world’s capital cities or sanctuaries of late prehistory and antiquity are located on the course of Salt Lines: Stonehenge, Avebury, Babylon, Assur, Niniveh, Thebes, Abu Simbel, Harappa, Mycenae, Athenes, Hattusa, Alesia, Teotihuacan, Chichén Itzá, Tiwanaku and Caral.
According to the author, such a situation challenges probability laws and can hardly be explained away by chance only, and thus is the result of some common knowledge held by the Megalithic civilization spreading to different parts of the globe.
Butler and Knight claim that the Megalithic Yard is a fundamental number for the Sun, the Moon and the Earth. The Megalithic arc second as measured on the Earth equator is very close to 366 Megalithic Yards, while the lunar Megalithic arc second as measured on the Moon equator is very close to 100 Megalithic yards, and the solar Megalithic arc second as measured on the Sun equator is very close to 40,000 Megalithic Yards.

French author Sylvain Tristan suggests that the numbers 366, 40 and 10 are not only fundamental to the Earth, the Moon and the Sun, but also to the human body and water. In the water-based Celsius temperature measurement system, which is directly linked to base-10 numeration, the average human body temperature is 36.6 degrees. On a scale where the absolute zero is defined as being minus 1,000 degrees, water boils at the temperature of 366 degrees, which points at something intrinsically fundamental in these numbers.'