Sometimes the highlights of a vacation happen by accident, and that’s how we discovered the Royal Tyrrell Museum in Drumheller, Alberta.

We’d planned a week-long stay in Banff National Park and Jasper National Park, complete with a side trip to Dinosaur Provincial Park in Patricia. I’d made reservations for the bus tour a month in advance. The Red Deer River Valley is home to one of the richest fossil beds in the world, and we wanted to see how the Canadian Badlands stacked up to their American cousins. That morning, we woke to the sound of pouring rain and a ringing phone—the park ranger was calling to explain that the tour road had washed out.

Well. What to do on a gray, wet day in Alberta? While planning this trip, I’d seen the Royal Tyrrell Museum in the Western Canada TourBook guide on the list of AAA GEM attractions in the area, but it seemed a waste to spend time indoors when we’d traveled 3,000 miles to see the beauty of the Canadian Rockies. Now we could barely see our car in the parking lot. A warm, dry place sounded like the best option.

The drive from Banff to Drumheller took about 3 hours, but there’s nothing more relaxing than a good road in the rain. The Trans-Canada Highway descended 2,000 feet out of the mountains into Calgary, where we took Highway 2 north toward Red Deer. Exiting onto Highway 72, we headed east for 60 miles across the open plains, passing only trucks and sodden cattle.

Near Drumheller, the prairie dropped away as suddenly as the cliff in a “Roadrunner” cartoon, and we blinked in amazement at the vast canyon of eroded buttes and hoodoos below—the Canadian Badlands. Highway 9 took a steep grade into town, and like every other tourist, we stopped for a picture of the “world’s largest dinosaur,” an 86-foot-high Tyrannosaurus rex with an observation deck in her mouth.

Finally—finally!—we reached the Royal Tyrrell Museum, a sprawling complex in the sandstone hills outside Drumheller. Having just seen the world’s largest roadside attraction and a goofy assortment of dino sculptures on every corner, I was beginning to worry about the museum’s claim as “one of the world’s largest displays of dinosaurs.” For once, an understatement. We stood in Dinosaur Hall, surrounded by nearly 40 prehistoric giants, and my husband could only whisper, “Wow.”

The quality and variety of exhibits at the Royal Tyrrell is truly dazzling, from enormous skeletons and life-sized replicas to bone beds, tracks and dinosaur eggs encased in stone. Some specimens are as tiny and delicate as birds, while the brontosaurus thigh bone stands taller than a man. Dioramas, models and video screens provide fascinating details about North American dinosaurs and early mammals, and you don’t have to be a paleontologist to enjoy the experience. There are plenty of hands-on activities for kids; the summer fossil-casting program is especially popular (reservations are suggested).

We strolled through the Cretaceous Garden, a rare collection of prehistoric plants from the swampy marshes that covered Alberta 70 million years ago. The Devonian Reef goes even deeper in history to the “Age of Fishes,” when this part of Canada was underneath a tropical sea. The weather wasn’t exactly balmy outdoors, but the rain had stopped, so we took a hike along the Badlands interpretive trail. During the summer, kids can excavate fossils and explore the trails with museum scientists.

If you’re ever near Banff, Calgary or Edmonton with a free day to spare, consider a drive to the Royal Tyrrell Museum. This world-class attraction may be out of the way, but it’s well worth the trip.