Atrium (formally known as "Atrium on Bay") is a large 1,000,000 square-foot retail and office complex in Toronto, Ontario, Canada. Atrium is located adjacent to the highly popular Yonge-Dundas Square, and was built upon the former site of the historic Ford Hotel Toronto, on the north side of Dundas Street West, extending from Yonge Street to Bay Street. The 14-floor, mixed-use building was constructed in 1981 with two levels of retail stores and restaurants.