Beneath Place d'Armes sits an Art Deco public toilet, built in 1934 as a Depression-era works project by Mayor Camilien Houde. It cost 50,000 dollars, spanned 270 square metres, and was finally closed in 1980 for reasons of, in the city's careful phrasing, morality and cleanliness.

The square itself is Montreal's second-oldest public site, first laid out in 1693 as a hay and wood market. At its centre, an 1885 monument honours founder Paul de Chomedey, flanked by a statue of soldier Raphaël-Lambert Closse and his dog Pilotte, who reportedly saved the colony more than once by waking the troops during Iroquois attacks.

VoiceMap's self-guided audio tours use Place d'Armes to trace the stories behind Notre-Dame Basilica, the Saint-Sulpice Seminary, the Bank of Montreal's domed headquarters, and the eight-storey building that became the city's first skyscraper.