Concept
Version 6
Created by Boundless
Neolithic Monuments
Source
Boundless vets and curates high-quality, openly licensed content from around the Internet. This particular resource used the following sources:
"640px-Avebury_(South_Inner_Circle),_Wiltshire,_UK_-_Diliff.jpg."
https://commons.wikimedia.org/w/index.php?curid=33014322
Wikimedia Commons
CC BY-SA 3.0.