Established in 1642 as a Roman Catholic mission, Montreal was named for the mountain where its French founders erected a cross. They also laid out the streets that today meander through three core districts: the Plateau, Downtown, and historic Old Montreal. The city has remade itself three times: first in the 1830s when planners decreed that all buildings be built with Trenton limestone; again in the 1870s when the city moved up the hill into what is called the Square Mile; a