This is a list of the oldest buildings and structures in Toronto, that were constructed before 1870. This corresponds to the first 75 years since the founding of York. The history of Toronto dates back to Indigenous settlements in the region approximately 12,000 years ago. However, the oldest standing structures in Toronto were built by European settlers. Remains of a Seneca settlement exist at the federally protected Bead Hill archaeological site, in eastern Toronto.
The first structure built by Europeans in Toronto was Magasin Royal, a French trading post established in 1720. In the 1750s, the French built several structures in the area (including Fort Rouillé), although the French would later destroy them in 1759, following their defeat at the Battle of Fort Niagara. In 1793, the government of Upper Canada arranged for the purchase of Toronto from the Mississaugas in order to settle newly landed British American colonists Loyalists, who were exiled from the United States of America after the Revolutionary War. Many of Toronto's oldest structures date back to this early period of British settlement, when it was known as York. The town of York was formally incorporated as the City of Toronto in 1834, with the passage of the Incorporation of the City of Toronto Act.
The oldest intact structure of European settlement may be a piece of St Paul's Cathedral's courtyard railing dating from 1714, designed by Christopher Wren, that is now part of John Howard's tomb in High Park. Howard had it shipped from London in 1875.
The following list does not include structures where only the facade of the building has been preserved. It also does not include the collection of buildings and structures collected at The Village at Black Creek. Those are listed at List of Village at Black Creek buildings.
Fort York was rebuilt after the original garrison was destroyed in the 1813 Battle of York. The site is a national historical site and its buildings, fortifications and cemetery are protected.
The new City of Toronto came into existence on January 1, 1834.