Place Bonaventure.

It depends on what you're after. If you're an architecture enthusiast, the exterior alone — 3.1 million square feet of raw Brutalist concrete, once the largest concrete building on Earth — rewards a walk around the perimeter. But the exhibition halls closed permanently in 2020, so there's no public attraction inside. The real surprise is the Hôtel Bonaventure Montréal on the roof, where a 2.5-acre garden with waterfalls and a heated outdoor pool sits 17 stories above the railway tracks.

You can walk through the public lobby and admire the exterior without paying anything. The building connects directly to the RÉSO underground network, so you'll likely pass through it anyway if you're moving between Bonaventure Metro and Gare Centrale. The rooftop gardens and pool, however, are reserved for hotel guests.

Take the Orange Line to Bonaventure Metro station — the building sits directly above it. You can also reach it on foot through the RÉSO underground city from virtually anywhere in the downtown core, following signs for "Place Bonaventure" or "Gare Centrale." The address is 800 De La Gauchetière Street West, and if you're driving, indoor parking is accessible via Mansfield Street at around $24 for 10 hours.

Since the exhibition halls closed in 2020, Place Bonaventure functions primarily as a commercial office complex. The Hôtel Bonaventure Montréal still operates on the roof, and the lower levels house some retail and food options connected to the underground city. Occasionally the former exhibition spaces host immersive pop-up events, but the days of the Montreal Boat Show and Salon du livre here are over.

The rooftop of the Hôtel Bonaventure Montréal is the thing most people walk right past. Seventeen stories above the street, a 2.5-acre garden with waterfalls, koi ponds, and a year-round heated outdoor pool hides on top of what looks like a concrete fortress — swimming outdoors in a Montreal January, surrounded by Brutalist walls, is genuinely surreal. From the street, look for the deeply textured, sand-blasted concrete ribbing on the facades; it's a tactile record of 1960s ambition you can literally run your fingers across.

The firm Affleck, Desbarats, Dimakopoulos, Lebensold, Sise — later known as ARCOP — designed it, with Raymond T. Affleck as lead architect. The associate in charge of design was Eva Vecsei, a rare example of female leadership on a mega-project in 1960s Canada. Her quote about the era captures the mood: "We were new; we saw no limits."

The complex spans 3.1 million square feet — roughly the area of 54 American football fields stacked together. When it opened in 1967, it was the largest concrete building in the world and the second-largest commercial building after Chicago's Merchandise Mart. The entire structure was built on a platform over 18 active railway tracks, without ever stopping train service below.

Yes, there's an indoor parking garage managed by Indigo, accessible from Mansfield Street. As of 2025, rates run $6 for 30 minutes, $12 for an hour, and $24 for up to 10 hours. An early bird rate of $15.75 applies if you enter between 4:00 AM and 8:30 AM. But the Metro station directly beneath the building makes driving unnecessary for most visitors to Montreal.