Toronto Rolling Mills William Armstrong. 1864. Pastel drawing. 73.2 x 103.2 cm. TPL (TRL) JRR 1059 The Toronto Rolling Mills, owned by Casimir Gzowski and Company, was the largest manufacturing plant in Toronto and the largest iron mill in Canada in the 1860s. It was located in the east-end of Toronto on Mill Street between Cherry (East) and Overend (Water) streets. One of several foundries manufacturing railway equipment, the mill made iron rails for Grand Trunk Railway lines until steel rails were produced in 1869. The mill was then dismantled, and Grand Trunk Railway and Standard Fuels later occupied the property. Mills like this one were a source of employment for many immigrants.