Olympic Stadium (French: Stade olympique) is a multi-purpose stadium in Montreal, Canada, located at Olympic Park in the Hochelaga-Maisonneuve district of the city. Built in the mid-1970s as the main venue for the 1976 Summer Olympics, it is nicknamed "The Big O", a reference to both its name and to the doughnut-shape of the permanent component of the stadium's roof. It is also disparagingly referred to as "The Big Owe" in reference the astronomical construction costs to the city and of the hosting of the 1976 Olympics as a whole. The tower standing next to the stadium, The Montreal Tower, is the tallest inclined tower in the world with an angle elevation of 45 degrees.

The stadium is the largest by seating capacity in Canada. After the Olympics, artificial turf was installed and it became the home of Montreal's professional baseball and football teams. The Montreal Alouettes of the CFL returned to their previous home of Molson Stadium in 1998 for regular season games, but continued to use Olympic Stadium for playoff and Grey Cup games until 2014 when they returned to Molson Stadium for all of their games. Following the 2004 baseball season, the Expos relocated to Washington, D.C., to become the Washington Nationals. The stadium currently serves as a multipurpose facility for special events (e.g. concerts, trade shows) with a permanent seating capacity of 56,040. The capacity is expandable with temporary seating. Club de Foot Montréal (formerly known as Montreal Impact) of Major League Soccer (MLS) has used the venue when demand for tickets justifies the large capacity or when the weather restricts outdoor play at nearby Saputo Stadium in the spring months.

The stadium has not had a main tenant since the Expos left in 2004. Despite decades of use, the stadium's history of numerous structural and financial problems has largely branded it a white elephant.

Incorporated into the north base of the stadium is the Montreal Tower, the world's tallest inclined tower at 175 metres (574 ft). The stadium and Olympic Park grounds border Maisonneuve Park, which includes the Montreal Botanical Garden, adjacent to the west across Rue Sherbrooke (Route 138).

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