Roundhouse Park, Railway park in Old Toronto, Canada

Roundhouse Park is a 6.9-hectare park in downtown Toronto built around the John Street Roundhouse, a brick and glass building with 32 wooden bay doors facing a 120-foot turntable. The park also holds the Toronto Railway Museum, Steam Whistle Brewing, the Rec Room, and a collection of locomotives and railway cars.

Canadian Pacific Railway built the John Street Roundhouse in 1929–1931 to replace an 1897 roundhouse on the same site. Anglin-Norcross erected the structure, and the Canadian Bridge Company supplied the 120-foot turntable, the largest on the CPR. It serviced locomotives until 1986, when the CPR donated it to the City of Toronto; a third was dismantled and rebuilt in 1995 for the Metro Toronto Convention Centre, and it was designated a national historic site in 1990.

The Toronto Railway Museum opened on May 28, 2010, in three stalls of the John Street Roundhouse. Its collection includes Canadian National No. 6213, a 4-8-4 built by Montreal Locomotive Works in 1942, and CP Rail 7020, an Alco S-2 from 1944. Outside, the miniature railway runs four cars plus a caboose, with tickets sold at the 1896 Don Station.

Enter from Bremner Boulevard or Lower Simcoe Street; the SkyWalk links the park directly to Union Station. The miniature railway runs in warmer months, with tickets sold at the 1896 Don Station. The 120-foot turntable and courtyard sit at the centre, ringed by the roundhouse bays.

The roundhouse's 120-foot turntable, built by the Canadian Bridge Company, was the largest on the Canadian Pacific Railway. It could position 32 locomotives at the 32 wooden bay doors of the inner curved facade. The coaling tower and water tank standing in the park are original working structures from the depot's steam era.