To experience the core of Montreal in 2026, three to four days is generally considered the "sweet spot." A three-day itinerary allows you to dedicate your first day to the historic charm of Old Montreal (Vieux-Montréal) and the Old Port, where you can explore cobblestone streets and the Notre-Dame Basilica. Day two is best spent in the Plateau and Mile End neighborhoods, enjoying local cafes, mural art, and the iconic view from Mount Royal Park. On your third day, you can head to the Olympic Park area to visit the Biodome or the Botanical Gardens. If you have a fourth day, it provides the perfect buffer to explore the "Underground City," visit the Museum of Fine Arts, or take a deeper dive into the city's world-class food scene, including non-negotiables like Montreal-style bagels and smoked meat.