new civic square. The businesses on that side of the street included two burlesque theatres, pawn shops and a cinema. The south side was vacant at the time of the City Hall opening but was eventually occupied by a new hotel, connected by a bridge over Queen Street to the square. To the west of the new City Hall, the University Avenue Armouries at University Avenue just north of Osgoode Hall was bought from the Government of Canada for million to make way for a new court building, also as part of the new civic square project. Opening and post-completion changes The building was officially opened to the public on September 13, 1965, by Georges Vanier, the governor general of Canada. The opening ceremony was attended by 14,000 dignitaries, including Lester B. Pearson, the prime minister of Canada, and John Robarts, the premier of Ontario. In 1990, Hester How Daycare Centre was opened in the building, and named after a Toronto teacher Hester How, who helped turn around delinquent boys in the second half of the 19th Century. City Hall was designated as a property of historical and architectural significance under the Ontario Heritage Act in 1991. Minor upgrades by Toronto architect Bruce Kuwabara to connect the two towers and upgrade council chambers from 1997 to 1998. A green roof was added late 2009 and opened to over 10,000 visitors on Doors Open Toronto weekend in May 2010. The site now contains largest publicly accessible green roof in the city. Design and features Exterior While the building's base is rectangular, its two towers are curved in cross-section and rise to differing heights. The east tower is 27 storeys () tall and the west tower is 20 storeys (). Between the towers is the saucer-like council chamber, and the overall arrangement is somewhat like two hands cradling the chamber. The outer surfaces of the curve are covered with concrete bearing a rib pattern that provides strength and prevents collapse of the fabric as a result of the expansion of the exterior surfaces, and the tearing apart of the fabric as a result of differences in air pressure on the two sides of each wing-like tower during the high winds characteristic of the Great Lakes. The north, west, and east elevations are more abstract and sculptural in contrast with the extensive glazing of south elevation facing the square; each presents a view