A 1969 centennial project, abruptly shuttered over roof concerns

The Ontario Science Centre

Raymond Moriyama's celebrated Don Valley building opened for Canada's 1967 centennial celebrations and ran for 55 years — until the province closed it in 2024, with a smaller replacement planned for Ontario Place by 2028.

Plans for the Ontario Science Centre were first announced by Premier John Robarts in 1964 as one of Ontario's projects for Canada's 1967 centennial. The Don Valley site was selected, and architect Raymond Moriyama — in his first major project — was commissioned to design it. The Centre opened to the general public on September 28, 1969.

A 2024 closure

The building was abruptly closed to the public on June 21, 2024, by the Ontario government, citing structural safety concerns related to the 55-year-old building's roof — though a government-commissioned engineering report on deteriorating roof panels had not recommended immediate closure, a decision Moriyama's own architecture firm publicly called "a political move." The province has announced plans to permanently relocate the Science Centre to Ontario Place as part of that waterfront site's redevelopment, with a smaller footprint and fewer staff, and an anticipated opening in 2028. The fate of Moriyama's original building remains unresolved.

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