I caught a really cool “Mysteryquest” episode on the History Channel about the “Sounds of Stonehenge.” There is some thought that Stonehenge was built like a stadium to amplify acoustics. Acoustics experts tested it to see how much the stone amplifies sounds like drumming used in ritual. They recreated ancient music at the site. When the drumming occurred, it bounced off the stones to sound like responding drum beats.
In 3100 BC, they began construction on Stonehenge but it took over 1400 years to complete, passed down through many many generations. Transporting without the wheel they moved blue stones 140 miles. They used carpentry skills in fitting the multi-ton boulders together. It was abandoned in 1000 BC. It was built to line up with the mid summer and mid winter solstices and to this day is a work of wonder and apparently acoustics.
Check out this clip from the show and then the other clip that shows a test on acoustics done at a replica site.