The inverted roller coaster—where the train travels underneath the track with the riders' seats attached directly to the wheel carriage—was invented by the Swiss design firm Bolliger & Mabillard (B&M). The concept was spearheaded by engineers Walter Bolliger and Claude Mabillard in the early 1990s. They collaborated with Jim Wintrode, then-general manager of Six Flags Great America, who envisioned a coaster that would simulate the feeling of flight without a floor. The very first inverted coaster, Batman: The Ride, opened at Six Flags Great America in 1992. In 2026, this design remains a gold standard for smoothness and intensity in the theme park industry. B&M’s innovation was revolutionary because it allowed for complex inversions and high-G maneuvers while providing an unobstructed view of the ground, a stark contrast to the "suspended" coasters of the 1980s that merely swung side-to-side. This invention birthed some of the most famous rides in the world, including Montu, Alpengeist, and Banshee.