Chateau Royale (formerly known as the Undermount Offices at Alexandra Square) is a mixed-use residential condominium and commercial complex located at 135 James Street South, in the downtown core of Hamilton, Ontario, Canada. The building is located in the centre of the city, bound by James Street to the west, and the Hamilton GO Centre to the north. The former office complex opened in 1966, and the newly formed residential tower officially opened in 2006.