Long-time readers of TDG will know that I'm very interested in archaeoastronomy (take a look at my essay on "The God With the Upraised Arm" as an example). MSNBC has just published a cool online feature titled "Ten ancient observatories spied from space" which is worth checking out.
Today, cutting-edge astronomers use space-based observatories to gain a sharp view of the stars and advance our understanding of the cosmos. But appreciation for celestial bodies dates back to ancient times. Many cultures built structures in ways that suggest they were in tune with Earth's annual trek around the sun. Other structures appear to take constellations and planets into account... Each page includes an image taken by GeoEye's Ikonos satellite, as it flew 423 miles above Earth at an average speed of 17,000 miles per hour.
Included are obvious sites such as Stonehenge and Chichen Itza, but also lesser known locations including Casa Rinconada and Chankillo.
Previously on TDG: Google Earth Tour of ancient and mysterious places.