If you have driven north along the Don Valley Parkway, one of Toronto’s major highways, you may have glimpsed a mysterious sight as you leave the downtown. Since 2010, two handsome monoliths have been rising next to the highway in the Don Mills neighbourhood. One is a torqued box of glimmering white stone; the other, a pale limestone disc capped by a crystalline blue dome. These mysterious volumes are two of Canada’s most remarkable new buildings. In September they will open as the Aga Khan Museum, a celebration of Islamic art and culture, and a new community centre and prayer hall for Ismaili Muslims.