May 27-28: Doors Open 2017
“The 18th annual Doors Open Toronto returns on Saturday, May 27 and Sunday, May 28, 2017, offering free and rare access to 150 architecturally, historically, culturally and socially significant buildings across the city”.
News release: Doors Open Toronto unveils exciting program for May 27 and 28
Read my post of the Door Open 2017 event
Free in Toronto 