# List of county courthouses in Ontario

The territorial distribution of judicial authority in Ontario dates to the early years of British rule following the Conquest of New France. In 1788 the government of the Province of Quebec divided the western portion of the colony into four "districts": Hesse, Nassau, Mecklenburg, and Lunenburg. Following the Constitutional Act 1791, these districts became the basis of the newly created Upper Canada. In 1792 the districts were renamed Western, Home, Midland, and Eastern. At this time the government began subdividing districts into counties, and counties into townships.
In October 1792, the Parliament of Upper Canada passed An act for building a gaol and court house in every district within this province. This law handed judicial power to districts and mandated the construction of a courthouse in each district town.
During the first half of the 19th century, the borders of districts, counties, and townships changed frequently from realignments, mergers, and newly created areas. In 1849 the government abolished the district system and transferred all judicial and administrative responsibilities to individual counties. Each county created a county seat, which served as its capital and was home to its courthouse. Following the 1849 abolition of districts, counties that did not possess a former district courthouse had to build a new edifice.
In the 20th century many of Ontario's historic counties were replaced by regional or metropolitan areas. The majority the province's 19th century courthouses still exist and have legal protection on the Canadian Register of Historic Places. Ontario's historic courthouses represent a diverse array of architectural styles, including Italianate, Romanesque, Greek Revival, Second Empire, and Art Deco.

## District courthouses (pre-1849)

| District | County | County Town | Built | Architect | Notes |
| Colborne | Peterborough | Peterborough | 1838 | Joseph Scobell | |
| Eastern | Stormont | Cornwall | 1826 | Archibald Fraser | |
| Johnstown | Leeds | Brockville | 1842 | John George Howard | |
| Kent | Kent | Chatham | 1848 | William Thomas | |
| London | Middlesex | London | 1827 | John Ewart | |
| Niagara | Lincoln | Niagara-on-the-Lake | 1846 | William Thomas | County seat moved to St. Catharines in 1862. The building is now known as the Court House Theatre and is used for the Shaw Festival. |
| Ottawa | Prescott | L'Orignal | 1825 | unknown | |
| Prince Edward | Prince Edward | Picton | 1832 | | |
| Victoria | Hastings | Belleville | 1838 | Thomas Rogers | Demolished in 1972. |
| Wellington | Wellington | Guelph | 1842 | Thomas Young | |

## County courthouses (post-1849)

| County | Seat | Built | Architect | Notes |
| Brant | Brantford | 1852 | John Turner | |
| Bruce | Walkerton | 1863 | David Murray | |
| Carleton | Ottawa | 1870 | Robert Surtees | Now used as the Ottawa Arts Court Theatre. The courthouse for the region is now the Ottawa Courthouse. |
| Dufferin | Orangeville | 1880 | Cornelius John Soule | |
| Elgin | St. Thomas | 1852, 1899 | John Turner, Neil Darrach (reconstruction) | Burned down in 1898. Rebuilt using parts of original. |
| Essex | Sandwich | 1855 | Albert Henry Jordan | Built by future Prime Minister Alexander Mackenzie. Now known as Mackenzie Hall. |
| Frontenac | Kingston | 1855 | Edward Horsey, John Power | In 1875 a fire destroyed the interior and the dome. The reconstructed interior and dome were designed by John Power and his son Joseph. |
| Grey | Owen Sound | 1852 | Bruce George | No longer used. |
| Haldimand | Cayuga | 1850 | Cumberland and Ridout | Burned down in 1922. |
| Haldimand | Cayuga | 1923 | Frank Barber | |
| Halton | Milton | 1854 | Clark and Murray | No longer in use. |
| Huron | Goderich | 1854 | Mellish Morrell and Russell | Based on the design of Waterloo County. Burned down in 1954. |
| Huron | Goderich | 1956 | Leonard Gordon Bridgman | |
| Lambton | Sarnia | 1852 | Alexander Mackenzie | Demolished in 1960. |
| Lanark | Perth | 1862 | Henry Hodge Horsey | |
| Lennox and Addington | Napanee | 1864 | John Power, Thomas Fuller | |
| Lincoln | St. Catharines | 1848, 1864 | Kivas Tully (town hall), John Latshaw (courts) | Built in 1848 as the St. Catharines town hall. When the county seat moved in 1864, an addition was made to house the courts. |
| Norfolk | Simcoe | 1863 | John Turner | No longer in use. |
| Northumberland | Cobourg | 1856 | Kivas Tully | Now Victoria Hall. A new courthouse for Northumberland County has been constructed. |
| Ontario | Whitby | 1853 | Cumberland and Storm | Now known as the Centennial Building. |
| Oxford | Woodstock | 1889 | Robert Brookes, Cuthbertson and Fowler | |
| Peel | Brampton | 1865 | William Kauffmann | Now houses the Peel Art Gallery, Museum and Archives. |
| Perth | Stratford | 1885 | George F. Durand | |
| Renfrew | Pembroke | 1862 | Henry Hodge Horsey | |
| Simcoe | Barrie | 1877 | George H. Brown | Demolished in 1976. |
| Victoria | Lindsay | 1862 | Frederic William Cumberland | |
| Waterloo | Kitchener | 1852 | Mellish and Russell | Demolished in 1965. |
| Welland | Welland | 1854 | Kivas Tully | |
| Wentworth | Hamilton | 1878 | Charles Willer Mulligan | Demolished in 1956. |
| York | Adelaide Street Courthouse | 1852 | Cumberland and Ridout | Served as courthouse until 1900. |
| York | Old City Hall, Toronto | 1900 | Edward James Lennox | York County functions transferred to Newmarket in 1953. Remained as principal courthouse for City of Toronto until 2023 when court services moved to 10 Armoury Street. |
| York | Newmarket | 1883 | Mallory & Sons | Became seat of York County in 1953 as a result of the creation of Metropolitan Toronto. After dissolution of York County in 1971 remained a town hall until 1975 and a courthouse until 1980 when court services moved to 50 Eagle Street. Now a cultural and social venue. |