In 1978, the workers of Sudbury's largest mining corporation, Inco (now Vale), embarked on a strike over production and employment cutbacks. The strike, which lasted for nine months, badly damaged Sudbury's economy. The city government was spurred to launch a project to diversify the city's economy. A unique and visionary project, Science North was inaugurated in 1984 with two-snowflake styled buildings connected by a tunnel through the Canadian shield where the Creighton fault intersects the shores of Lake Ramsey. The city tried to attract new employers and industries through the 1980s and 1990s with mixed success. The city of Sudbury and its suburban communities, which were reorganized into the Regional Municipality of Sudbury in 1973, was subsequently merged in 2001 into the single-tier city of Greater Sudbury. In 2006, both of the city's major mining companies, Canadian-based Inco and Falconbridge, were taken over by new owners: Inco was acquired by the Brazilian company CVRD (now renamed Vale), while Falconbridge was purchased by the Swiss company Xstrata, which itself was purchased by Anglo–Swiss Glencore, forming Glencore Xstrata. Xstrata donated the historic Edison Building, the onetime head office of Falconbridge, to the city in 2007 to serve as the new home of the municipal archives. On September 19, 2008, a fire destroyed the historic Sudbury Steelworkers Hall on Frood Road. A strike at Vale's operations, which began on July 13, 2009, was tentatively resolved in July 2010. The 2009 strike lasted longer than the devastating 1978 strike, but had a much more modest effect on the city's economy than the earlier action—unlike in 1978, the local rate of unemployment declined slightly during the 2009 strike. The ecology of the Sudbury region has recovered dramatically, helped by regreening programs and improved mining practices. The United Nations honoured twelve cities in the world, including Sudbury, with the Local Government Honours Award at the 1992 Earth Summit to recognise the city's community-based environmental reclamation strategies. By 2010, the regreening programs had successfully rehabilitated of land in the city; however, approximately of land have yet to be rehabilitated. Geography Sudbury has 330 lakes over within the city limits. The most prominent is Lake Wanapitei, the largest lake in the world completely contained within the boundaries of a single city. Ramsey Lake, a few kilometres south of downtown Sudbury, held the same record before the municipal amalgamation in 2001 brought Lake Wanapitei fully inside the city limits.