In 1887, extravagant parties marked the inauguration of the Saint-Antoine-de-Padoue, which became the Co-cathedral of the Saint-Jean-Longueuil diocese in 1982. Its architecture is Gothic Revival, and its dome, neo-Byzantine style. The building became a heritage building in 2012. According to Quebec Heritage, the Co-cathedral is a heritage place of worship, which gives it a unique character and lists it among top-rated buildings of the province. On the other hand, the museum contains objects dating back to the origins of the parish, 1697.