100 King Street West, Office skyscraper in downtown Hamilton, Canada

100 King Street West is a 25-storey, 103-metre office tower completed in 1972, part of the Lloyd D. Jackson Square complex. Its facade alternates horizontal rows of Stelcoloy steel and glass windows. The lobby has granite floors, a security desk, a digital directory and two steel-clad elevator banks: four Otis cars on the east side serve floors 2 to 14, five on the west side serve floors 15 to 24.

The tower was built as the head office of Stelco, then Canada's largest steel producer and one of Hamilton's biggest employers, and was completed in 1972. Stelco used the building to demonstrate steel's versatility and to showcase Stelcoloy, an alloy designed to rust slowly into a protective layer.

The tower's name comes from its address at 100 King Street West, and it was long known as Stelco Tower after the steel company that built it. The lobby connects directly to Jackson Square mall and three other office buildings, so the site functions as an indoor pedestrian hub in the downtown core.

The lobby on the ground level connects directly to Jackson Square mall and the three other office buildings in the complex, and escalators and stairs lead up to the plaza level. A common underground garage holds 1300 vehicles. The tower stands at 100 King Street West in downtown Hamilton.

Stelco used the tower to showcase Stelcoloy, a steel alloy meant to rust slowly; the oxidation layer protects the metal from further damage and gives the facade its self-colouring. The steel was grey-blue when the building went up in 1972, and the mail chute inside is a rarity in a modern skyscraper.