The Manchester cotton exchange was the cornerstone in the trade of this fibre - a building to which the city used to owe its prosperity. The pure water from the Pennines, the high water table and a large workforce also helped the cotton industry to prosper. The cotton value on the cotton exchange's last ever day of trading is still there for every one to see, high up on a board on the wall. Today this huge hall is partly taken up by the 700 seats of the Royal Exchange Theatre.