Charming montreal is actually two cities in one theres the city everyone knows with its old world accents and then theres the underground city known as reso this 15 hour guided tour explores the citys popular above ground sites and the subterranean city where 500 000 people circulate daily among 2 000 shops hotels bars and restaurants learn about the engineering behind this underworld as you explore the various nooks below one of canadas most dynamic cities