St. Lawrence Hall
Designed by William Thomas, in the Renaissance tradition, this hall, built by the city in 1850, was for many years Toronto's chief social and cultural centre. With its handsome Corinthian facade and graceful cupola, it ranks amongst the finest of 19th century Canadian public buildings.
Its assembly room was used for lectures, concerts, balls and receptions; here such noted Canadians as Sir John A. Macdonald, George Brown, and Thomas D'Arcy McGee addressed Toronto audiences. After a long period of disuse and neglect, it was restored in 1967 as a centennial project.
Plaque via Alan L. Brown's site Toronto Plaques. Full page here.