Toronto's Old City Hall was one of the largest buildings in Toronto and the largest civic building in North America upon completion in 1899. It was the burgeoning city's third city hall. It housed Toronto's municipal government and courts for York County and Toronto, taking over from the Adelaide Street Court House. York County offices were also located in Old City Hall from 1900 to 1953. With the establishment of Metropolitan Toronto, the county seat moved to Newmarket, Ontario (and to the Old Newmarket Town Hall and Courthouse).

Designed by prominent Toronto architect Edward James Lennox, the building took more than a decade to build and cost more than $2.5 million. Work on the building began in 1889. It was constructed of sandstone from the Credit River valley, grey stone from the Orangeville, Ontario area, and brown stone from New Brunswick. Angry councillors, due to cost overruns and construction delays, refused E.J. Lennox a plaque proclaiming him as architect for the completed building in 1899. Not to be denied, Lennox had stonemasons "sign" his name in corbels beneath the upper floor eaves around the entire building: "EJ LENNOX ARCHITECT AD 1898".

It is currently a county courthouse, lease to expire in 2016