Toronto Power Generating Station
By far the most beautiful abandoned building I've visited was this one. Unlike other large industrial buildings, this was no large homogenous box. This had a sense of design — an architectural vision. Opened in 1906, this hydro-electric power station was designed by Toronto architect E.J. Lennox and sits on the banks of the Niagara River, just up from Niagara Falls.
The station was built for the Electrical Development Company of Ontario to supply 25-cycle power to Toronto. Construction began in 1903 and it operated from 1906 until 1974. In 1983 it was designated as a national historic site in Canada.
For its time, it represented a milestone in engineering and technology. Hydro-electric power — at this scale — was a significant industrial accomplishment. This explains why the building itself was designed as a tourist landmark. Designed in the Beaux-Arts style, it featured gorgeous tiled mosaic floors, polished copper railings and a palatial facade. From the exterior you'd never guess this was a power station.
Today, the site has the ridiculously long official name The Electrical Development Company and Powerhouse National Historic Site of Canada. Ownership was transferred to the Niagara Parks Commission in 2007 and the site is being assessed to explore re-use options in the future.