The Toronto Railway Museum occupies three stalls of the John Street Roundhouse at Roundhouse Park, a 6.9-hectare (17-acre) site in Toronto''s former Railway Lands directly south of the CN Tower. The roundhouse was built in 1929–1931 by Anglin-Norcross for the Canadian Pacific Railway, replacing an earlier 1897 structure, and serviced the passenger locomotives running through nearby Union Station. Trains were kept in such condition here that railroaders spoke of a distinctive "John Street polish." The building was last used for its original purpose in 1986, after which the CPR donated it to the City of Toronto.

The semicircular building is wrapped by 32 bay doors facing a 120-foot (37 m) turntable — the largest the CPR ever owned, built by the Canadian Bridge Company. After one-third of the structure was dismantled to allow the Metro Toronto Convention Centre to be built below, that portion was reconstructed in 1995 (now Steam Whistle Brewing); the remaining two-thirds was rehabilitated by IBI Group Architects to house the museum and Cineplex''s Rec Room. The John Street Roundhouse was designated a National Historic Site of Canada in 1990.

The museum is operated by the Toronto Railway Historical Association (TRHA), a federally registered charity established in 2001, and opened on May 28, 2010. It tells the story of how rail propelled Toronto from a small town into Canada''s economic engine, combining an indoor exhibit and working restoration shop with a fleet of full-size locomotives and rolling stock displayed in the surrounding park.

The 120-foot CPR turntable and the curved façade of 32 wooden bay doors are the most photogenic compositions on site, especially with the CN Tower rising directly behind the roundhouse. CN 6213, the big green-and-black 4-8-4, is the standout locomotive subject and is easy to frame from several angles in the park. The restored railway village — Don Station, Cabin D signal cabin, the watchman''s shanty, water tower, and coaling tower — offers period detail, while the open park layout means the outdoor equipment can be photographed freely without an admission ticket. For the cleanest light on the east-facing locomotives, mornings work best.

Roundhouse Park gathers a remarkable roster of preserved equipment in the shadow of the CN Tower. The signature exhibit is Canadian National 6213, a U-2-G class 4-8-4 "Northern" steam locomotive built by Montreal Locomotive Works in 1942 and previously displayed for decades at Exhibition Place. Around it stand a cross-section of mid-century motive power: Canadian Pacific 7020 (an Alco S-2 of 1944), Canadian National 4803 (a GMD GP7 of 1953), Canadian Pacific 7069 (a Baldwin DS-4-4-1000 of 1948), the cab of CN 9159 (a GMD F7 of 1951), and a 1906 H.K. Porter 0-4-0 fireless industrial locomotive.

Passenger-car fans will find the Canadian Pacific "Cape Race" observation-sleeper (1929), the CP "Jackman" sleeper (1931), and the Dominion Atlantic dining car "Nova Scotia" built in 1896. Freight equipment includes Toronto, Hamilton & Buffalo steel-sheathed caboose No. 70 (1921), a 1917 CP "Fowler" boxcar, a wooden Reinhart Vinegars tank car (1938), and the Toronto Terminals Railway Pyke self-propelled crane. A restored GO Transit Hawker Siddeley RTC-85SP/D cab car from 1967 records the region''s commuter-rail history.

Inside the roundhouse, visitors can take the controls of a full-size diesel cab simulator set on 1950s Toronto trackage — setting speed, applying the brakes, and blowing the horn with real levers — while volunteers continue restoration work visible from the museum floor.

Plan on roughly one to two hours to take in the indoor exhibits, the cab simulator, and the rolling stock arrayed around the park. Admission to the Stall 17 museum is modest, and Roundhouse Park itself is free to walk through, so the locomotives and railway village can be enjoyed even outside museum hours.

During the warmer months the site comes alive with the Roundhouse Park Miniature Railway, which loops half a kilometre through the park in front of the museum. The ride is hauled by a replica steam locomotive or a replica Canadian Locomotive Company Whitcomb centre-cab diesel, with four cars seating four passengers each plus a caboose; tickets are sold at the restored 1896 Don Station, which doubles as the gift shop. Seasonal guided tours of the outdoor rolling stock and turntable rides round out the experience.

The setting is decidedly urban: the park sits among downtown towers, with the CN Tower, Rogers Centre, and Ripley''s Aquarium all a few minutes'' walk away, making the museum an easy stop on a broader downtown itinerary.