Mississauga is one of Canada's largest cities — and while its suburban sprawl has consumed most evidence of its past, the surrounding region holds a remarkable concentration of WWII industrial heritage, Victorian psychiatric campuses, and 19th-century correctional institutions. A 1940s WWII firearms inspection factory still stands in the heart of the city. A vast psychiatric hospital on Lake Ontario once held 4,000 patients. Here are 5 of the best abandoned places near Mississauga, selected from our Abandoned Places Map Canada — 2,500+ GPS locations across Canada.
Why Mississauga Is a Hidden Gem for Urban Exploration
Despite being one of the most rapidly developing urban areas in Canada, Mississauga's surrounding region contains significant concentrations of WWII industrial heritage, Victorian institutional campuses, and Credit Valley rural ruins within easy driving distance. The GTA's development pressure means many of these sites are temporary — visit while they stand.
1. Small Arms Inspection Building – Mississauga, Ontario — 1940 WWII Firearms Inspection Factory, Original Industrial Shell Still Standing in Port Credit (Known Location)
Built in 1940 as part of Canada's WWII war production effort, the Small Arms Inspection Building in Port Credit was where Lee-Enfield rifles and Bren guns were inspected before shipment to Allied forces. The massive low-rise industrial building with its distinctive sawtooth roofline is one of the last surviving examples of WWII war production architecture in the Greater Toronto Area. Now partially used as a cultural hub while sections remain in atmospheric semi-abandonment. The most historically significant WWII industrial building accessible from Mississauga and one of the best abandoned places in the city.
🔗 Learn more: Wikipedia – Small Arms Inspection Building
2. Whitby Psychiatric Hospital – Whitby, Ontario — One of Ontario's Largest Mental Health Campuses, Closed 1995, Original Ward Buildings in Advanced Decay, 45 Minutes from Mississauga (Known Location)
The Ontario Hospital at Whitby was one of the largest psychiatric institutions in Ontario — a complete self-sustaining campus that held thousands of patients through the mid-20th century before deinstitutionalization progressively emptied it. Closed in 1995, the original ward buildings, administration tower, and farm campus infrastructure decay across the Whitby site. A reputation for paranormal activity has made it one of the most discussed abandoned places in the GTA urbex community. One of the most atmospherically powerful abandoned places near Mississauga. Exact location available on our Abandoned Places Map Canada.
🔗 Also read: Top 5 Best Abandoned Places in Canada →
3. Ontario Reformatory Guelph – Guelph, Ontario — 1910 Self-Sustaining Prison Farm, Closed 1970s, Cell Blocks and Farm Buildings Still Standing, 1 Hour from Mississauga (Known Location)
The Ontario Reformatory at Guelph was a complete self-sustaining correctional institution — a working prison farm with cell blocks, workshops, greenhouses, and agricultural operations across several hundred acres of Wellington County land. Closed in the 1970s, the original cell block buildings, the Gothic Revival administration tower, and the farm infrastructure still stand across the Guelph site. One of the most architecturally distinctive and historically significant abandoned correctional facilities in Ontario. Exact location available on our Abandoned Places Map Canada.
4. Abandoned Credit Valley Limestone Mill – 1850s-1870s Stone Mill on the Credit River, Mill Race and Wheel Pit Still Visible, Halton Hills (Exclusively on Our Map)
An 1850s-1870s limestone grist mill on the Credit River in Halton Hills — the original cut-stone construction still largely intact, the mill race channel still traceable along the riverbank, and the wheel pit opening marking where the waterwheel drove the millstones. Credit Valley mills were the economic anchors of every 19th-century Ontario community west of Toronto; when the railway bypassed the Credit Valley route, these mills lost their markets within a generation. One of the most atmospherically beautiful abandoned places near Mississauga for Credit Valley industrial archaeology. Exact location available on our Abandoned Places Map Canada.
5. Abandoned Niagara Escarpment Farmstead – 1880s-1900s Ontario Stone Farmhouse and Bank Barn, Escarpment Forest Advancing, Halton Region (Exclusively on Our Map)
An 1880s-1900s Ontario farmstead on the Niagara Escarpment in Halton Region — the original fieldstone farmhouse with its Ontario Gothic roofline, the large bank barn with hand-hewn timber frame, and the escarpment forest advancing across what were once productive farm fields. Rural depopulation and the suburban expansion of the GTA emptied dozens of Halton escarpment farmsteads through the 20th century; their stone construction preserves them longer than wooden farmhouses elsewhere. One of the best abandoned places near Mississauga for Ontario agricultural heritage photography. Exact location available on our Abandoned Places Map Canada.
Safety Tips
- Development pressure: the GTA's real estate market moves fast — always verify current site status before visiting; sites can change from abandoned to active construction overnight
- Asbestos: universal in pre-1980 Ontario institutional and industrial buildings — always wear an FFP2 mask
- Never explore alone — always bring at least one other person
The urbex code applies everywhere: "Take nothing but photographs, leave nothing but footprints."
❓ FAQ
What is the most famous abandoned place near Mississauga?
The Small Arms Inspection Building in Port Credit — a 1940 WWII firearms inspection factory where Lee-Enfield rifles and Bren guns were inspected before shipment to Allied forces. One of the last surviving examples of WWII war production architecture in the GTA.
What was Whitby Psychiatric Hospital?
One of Ontario's largest psychiatric campuses, holding thousands of patients through the mid-20th century before deinstitutionalization progressively emptied it. Closed in 1995; original ward buildings decay across the Whitby site. One of the most discussed abandoned places in the GTA urbex community.
Why does the Credit Valley have so many abandoned mills?
The Credit River and its tributaries powered dozens of grist mills, sawmills, and woollen mills through the mid-19th century serving the agricultural communities of what is now Halton and Peel. When the Grand Trunk Railway chose the lakeshore route over the Credit Valley in the 1850s, valley communities lost their economic advantage and many mills became unviable within a generation.
🎯 Summary
The abandoned places near Mississauga range from a WWII firearms inspection factory in Port Credit to a vast psychiatric hospital campus in Whitby and 19th-century limestone mills hidden in the Credit Valley. Each of these 5 abandoned places near Mississauga captures a different layer of the GTA's layered industrial and institutional past.
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