Downtown Calgary is one of the fastest growing metropolitan areas in Canada with an economy centred around the oil industry. Calgary is the largest city in Alberta, on the east side of the Rocky Mountains with an elevation downtown at approximately 1048 metres (3440 feet) above sea level. The larger companies that occupy downtown Calgary include Petro-Canada, Shell Canada, Imperial Oil, Suncor Energy, TransCanada and the Canadian Pacific Railway. CP Rail moved its head office to Calgary in 1986, and is now among the city’s top employers.