10 Scariest Thrill Rides on the Planet

Brace Yourself: First opened in 2002 as the world’s first “fourth-dimensional” ride, with 360-degree rotating seats and headfirst, facedown drops, Six Flags Magic Mountain’s X was closed in 2007 for a $10 million rejiggering. This May it has emerged, phoenixlike and more spine-tingling than ever, with new immersive tunnels, more audio and visual enhancements, and sleeker wing-shaped trains. For the uninitiated, it’s called four dimensional, or 4-D, because the seats extend off the track to the sides, allowing riders to independently rotate head over heels, forward and backward—giving that mind-bending dimensional effect.

If You Chicken Out: Take a ride on the classic coaster Revolution. As recognized by the American Coaster Enthusiasts, it is "the world’s first modern vertical looping roller coaster with tubular steel track." It changed roller coasters forever.