Sir John A. Macdonald Building, Federal heritage building at Wellington Street, Ottawa, Canada

The Sir John A. Macdonald Building is a Beaux-Arts limestone and granite structure on Wellington Street in Ottawa, with three street frontages and its main entrance facing Parliament's West Block. It houses conference rooms and meeting spaces used for House of Commons business and official ceremonies.

The building opened in 1930 to a design by architect E.I. Barott and was originally built as a branch of the Bank of Montreal. The federal government later acquired it and converted it for parliamentary use.

The building's name honours Sir John A. Macdonald, Canada's first prime minister, since its renaming on January 11, 2012. In March 2024 it hosted the lying-in-state of former prime minister Brian Mulroney, an event open to the public. The carved exterior shows scenes of Canadian industry and architecture instead of classical figures.

The building sits on Wellington Street right next to the Parliament buildings and is easy to spot from the street. Because it is an active government building, access inside may be limited and security checks are likely required.

The building's three frontages follow a slope: the Sparks Street door sits a full storey below the Wellington Street entrance. That lower level is clad in granite, the upper in limestone. In March 2024 Brian Mulroney lay in state here before his funeral.