Answer:
The research of archaeologist in the written form.
Step-by-step explanation:
The documents which was written by many archaeologist after studying the Stonehenge is the main source which is used for the understanding of building of Stonehenge. According to archaeologist John Aubrey who made a claim in the 17th century after studying Stonehenge that Stonehenge was built about 2500 BC ago by the Celtic high priests called the Druids.