Around 800,000 every year
There are several theories. see http://en.wikipedia.org/wiki/Stonehenge#Stonehenge_3_I_.28ca._2600_BC.29
Stonehenge is in the south of England - to the west of London and north of Salisbury.
See the Related Question.
Stonehenge is on Salisbury plain in Wiltshire, England. See "Related links."
See related link for information about Stonehenge.
This kind of information is very easy to find. And if you want to see how Stonehenge looked when it was constructed see the link below.
Stonehenge is on Salisbury plain in the county of Wiltshire in England. See "related links."
The main evidence for the existence of Stonehenge is that it's still there, and you can go to the Salisbury plain and actually see it.
Stonehenge was built by Neolithic people about 4500 years ago. The term "Cave men" is inaccurate since the people who built Stonehenge did not live in caves. See the timleine on the link below.
a lot
See related link.
Exactly where it is now, Stonehenge has not been moved. But for the idea behind its desgn see the link.