Deep within the rugged Kicking Horse Pass of Yoho National Park, the Spiral Tunnels stand as a monumental testament to human ingenuity. Originally, this steep section of the railway was known as the "Big Hill," a perilous challenge for early trains. To conquer the deadly grade, engineers in 1909 carved two massive tunnels inside the mountains themselves, inspired by the Swiss Alps. Today, this site offers one of the most unique spectacles in the world. Watch in awe as massive freight trains disappear into the mountain, only to re-emerge hundreds of feet higher or lower moments later. If you are lucky enough to see a long train, you might witness the rare "figure-eight" effect—where the locomotive crosses directly over its own tail, looping like a giant steel snake through the rock. It is a mesmerizing display of history and engineering in action.