Mont-Royal is the hill the city is named for and the reason Montreal has a horizon worth looking at. Frederick Law Olmsted — the man who built Central Park — laid out these slopes to feel like wild Laurentian forest dropped onto downtown's doorstep, and walking it is the closest the island gets to leaving itself.
About five and a half kilometres, and a genuine climb — best in the afternoon when the light goes long over the towers. Start at the Cartier monument off Avenue du Parc, where the drummers gather on summer Sundays, and take Chemin Olmsted up. It's the carriage road Olmsted graded so gently you barely notice the height you're gaining; let the staircase-shortcutters pass you.
The Chalet du Mont-Royal sits at the top, and the Kondiaronk lookout in front of it is the payoff — the whole grid and the St Lawrence laid flat below. Walk east to the cross, then down through the meadows to Lac aux Castors. Finish in the cemetery woods, loud with birds in May, and back down to the metro.