Early stages of subway construction turned Yonge Street into a large trench as this 1951 view from Louisa Street shows.

Early stages of subway construction turned Yonge Street into a large trench as this 1951 view from Louisa Street shows.

Yonge Subway construction. Steam shovels and trucks worked under street decking to complete excavations.

Yonge Subway construction. Steam shovels and trucks worked under street decking to complete excavations.

Happy Holidays from the TTC.

Happy Holidays from the TTC.

Ontario Premier Leslie M. Frost (left) and Toronto Mayor Allen Lamport activate a symbolic signal to officially open the Yonge Subwa, March 30, 1954.

Ontario Premier Leslie M. Frost (left) and Toronto Mayor Allen Lamport activate a symbolic signal to officially open the Yonge Subway,  March 30, 1954.

Hundreds of Torontonians attend the opening of the Yonge Subway at Davisville Station, March 30, 1954.

Hundreds of Torontonians attend the opening of the Yonge Subway at Davisville Station, March 30, 1954.

The Gloucester Railway Carriage and Wagon Company built 134 steel and 6 aluminium-bodied cars for the original Yonge Subway.

The Gloucester Railway Carriage and Wagon Company built 134 steel and 6 aluminum-bodied cars for the original Yonge Subway.