Although the St. Sulpice Seminary (Le Séminaire de Saint-Sulpice) is closed to the public, it's worth stopping by and admiring its exterior as you explore Old Montréal. On the Place d'Armes, and next to the Notre-Dame Basilica, this is Montréal's oldest building, completed in 1687. Its greystone facade with classical details is a rare survivor of French colonial architecture. The seminary's gardens are also the oldest surviving gardens in North America. Priests trained in this building for the task of converting the indigenous people of Canada to the Roman Catholic faith, and remarkably, the seminary is still in operation more than three centuries later.