At the turn of the 20th century, a small group of Torontonians envisioned a museum in the city of international stature. People of some position and influence, they championed the cause and persuaded both the Government of Ontario and the University of Toronto to fund the future museum.
The Royal Ontario Museum was formally created by the signing of the ROM Act in the Ontario Legislature on April 16, 1912. When the Duke of Connaught, then Governor-General of Canada, opened the new building to the public at 3:00 pm on March 19, 1914, it instantly became an object of pride for Toronto.
Today, the graceful structure of buff-coloured brick and terracotta, designed by Toronto-based architects Darling and Pearson, is the west wing of the ROM’s 
ensemble of buildings. Flanking Philosophers’ Walk, with its main entrance on Bloor Street West, this historic building originally housed five separate museums: the Royal Ontario Museums of Archaeology, Palaeontology, Mineralogy, Zoology, and Geology.
The intervening years brought several expansions. By the late 1920s, collections and staff were competing for space and the crowding had become intolerable. The first addition took place during the Great Depression and an effort was made to use mostly local building materials. Excavation was done by hand, using picks, shovels, and horse-drawn wagons. On October 12, 1933, Toronto newspapers reported that a newly opened wing facing Queen’s Park was a “masterpiece of architecture”.
In 1955, the five museums were reorganized as a single body and in 1968, the ROM was formally divided from the University of Toronto and became a separate entity under the provincial government.
A $55 million renovation was begun in 1978, intended to provide for the greatly extended research and collection activities and included a new curatorial centre, a new library and other facilities. Her Majesty Queen Elizabeth officially opened the new exhibition and gallery space, the Terrace Galleries, in a 1984 ceremony.
On June 3, 2007, the ROM opened the Michael Lee-Chin Crystal, a distinctive new symbol of Toronto for the 21st century. The Lee-Chin Crystal marks the beginning of a new age for the ROM, announcing the Museum as the country’s premier cultural and social destination.