36 different locations, Green Island was confirmed as the new location of Ottawa City Hall on January 31, 1956. The official sod-turning ceremony was held on September 16, 1956. Construction was completed in 1958. City Council held its first meeting at the new location on July 21, 1958. Princess Margaret officially opened the stone and glass building, which featured a marble spiral staircase leading to the second floor, on August 2, 1958. This building remained Ottawa’s City Hall until municipal amalgamation came into effect on January 1, 2001. The building of an expensive addition to the city hall (designed by Moshe Safdie), the architect of the National Gallery of Canada shortly before the building was decommissioned was a source of controversy in the city. References Landforms of Ottawa River islands of Ontario