Stonehenge is nearly five thousand years old; it’s one of over a thousand circles of standing stones that can be found throughout the British Isles and Europe. On the first day of summer, the sun rises over an outlying heelstone, as viewed through a central arch of stones. Other old observatories around the world mark the sun’s seasonal positions. In ancient Egypt, temples were built so that at the summer solstice, the sun’s rays shone through tall columns to sanctuaries within. At the Bighorn medicine wheel in Wyoming, piles of carefully placed stones pointed toward the summer sunrise. For hundreds of years in New Mexico, a slender ray of sunlight – the sun dagger of the Anasazi – sliced through a petroglyph spiral on the first day of summer. And there is the Sun Temple, built by the Incas at Machu Pichu – but of course Peru is south of the equator, and now it is the winter solstice sun that is framed in this ancient observatory’s window.