In the 1920s, its most prosperous era, the Port of Montréal built leading-edge infrastructure, including the refrigerated warehouse and refrigeration plant on the north side of the Clock Tower basin. With its 3,000 concrete pillars and ammonia compressors, the warehouse was a key structure for the port, both physically and functionally. The refrigeration system was used for storing meat, fruits and vegetables. The four towers on the roof housed water tanks for the sprinkler system. After the refrigeration plant was closed in 1965, one of the towers was used for storing pickling brine. The refrigerated warehouse shut down entirely in 1978. Declared a historic monument by the federal government in 1996, the old warehouse has since been converted into a commercial/residential complex.