The pavilion was built in 1898 to serve as the central hall for the Central Canada Exhibition. Designed by Moses C. Edey, it was inspired by London's Crystal Palace. It was named after Governor General Lord Aberdeen who presided over its opening. The structure was built by the Dominion Bridge Company, and took only two months and $75,000 to complete. The structure consists of a series of large steel arches holding up the roof. This allows for a large and column-free interior space of some 3,000 square metres (32,000 sq ft).

For many years, the main purpose of the structure was for agricultural shows, and from this came its "Cattle Castle" nickname. In wartime, the building became an important military structure. It was the home of Strathcona's Horse before they departed for the Boer War. In the First World War, it was the mustering point for Princess Patricia's Canadian Light Infantry, and it served as a general recruiting centre and the home to the Cameron Highlanders of Ottawa and the 4th Princess Louise Dragoon Guards during the Second World War.

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