One of the interesting things about this reconstruction of Stonehenge is the shadows cast by the standing stones.  In the past thirty years of doing archaeoastronomy, archaeologists have learned that shadows, and the way they move on important days, like the solstices and equinoxes, can be as important as shafts of light.  

http://www.english-heritage.org.uk/visit/places/stonehenge/Stonehenge reconstruction