The above is an overall map of Montreal, showing that it is actually situated on an island, with the St. Lawrence on the southern side, and the Riviere des Prairies on the north. But the latter river only separates Montreal from Laval, itself separated from the "mainland" by the Riviere des Mille Iles (River of a Thousand Islands - presumably something of an exaggeration).
Downtown Montreal is to the left of Parc Jean-Drapeau, a former Mayor of the city. And downtown is where the Jazz Festival is held, and also where we stayed.