Ancient Britons, over a period of well over thousand years. It was built and altered in several stages over the centuries. If the Druids used it at all, they were certainly not the first users.
It was not used as a barometer.
used for a clock
Pagans.
At Stonehenge human remains were found as well as tools used to help constructing the henge.
limestone
Stonehenge has not been used for thousands of years so no one knows the answer to this.
Stonehenge has no official ceremonial use today, other than a tourist attraction.
clay
sightseeing and tourism.
stonehenge
Stonehenge was used to track the stars and, therefore, could be also identify the time of year it was.
Stonehenge is in the country, but there is a guided audio tour and a giftshop on the Stonehenge site.