Alexis Nihon Complex is a 223,000 m2 (2,400,000 sq ft) building complexe situated at the border of Downtown Montreal, Quebec, Canada and the neighbouring city of Westmount, consisting of a shopping mall, two office towers, and a residential building. Although the complex is typically associated with Downtown Montreal and its main entrance on Atwater Avenue is in Montreal proper, more than 80% of the land it occupies is located in Westmount. It is named after the inventor and businessman Alexis Nihon. The shopping mall is directly connected to the Atwater metro station, which joins the building by a short tunnel with the adjacent Dawson College, and by a longer one adjoins nearby Westmount Square. The original complex was designed by the Montreal architect Harold Ship, and its architectural plans are housed at the Canadian Centre for Architecture.

Westmount is an affluent municipality on the Island of Montreal, in southwestern Quebec, Canada. It is an enclave of the city of Montreal, with a population of 19,658 as of the 2021 Canadian census.