 It was the first lock to be built out of concrete, and at the time was the largest structure ever built in the world with unreinforced concrete.Construction was by Corry and Laverdure of Peterborough, which excavated the site and built the concrete towers and lock, and Dominion Bridge Company of Montreal, which completed the metal work including rams, presses and large caissons, and was finished in 1904.The lift lock officially opened to the public to a crowd of thousands on 9 July 1904, and remains in full use today.