Use of English PRO

Hadrian's Wall (0) IS a limestone and sandstone structure, (1) ............ stretches for more than one hundred kilometres across the island of Great Britain, separating modern-day Scotland (2) ............ England. It was built almost two thousand years (3) ............ by the Roman army under orders from the emperor Hadrian. Some people think it was built to protect and separate the Romans from (4) ............ barbarians of the North while others believe it was to act simply (5) ............ a border to control immigration and smuggling. Whatever its reason (6) ............ being, Hadrian's Wall represented the final frontier of the Roman Empire. Many tourists come to see the wall each year and it is possible to climb and stand (7) ............ the parts of the wall and, in the summer months, it is possible to walk along (8) ............ entire length, from East to West.