Artist EJ Hill created this massive Brake Run Helix installation inside of the MASS MoCA (Massachusetts Museum of Contemporary Art... which looks fantastic). It is a working rollercoaster that holds exactly one person and doesn't run that often. I love the museums writeup:

In Brake Run Helix, Hill inverts the experience of riding a roller coaster, transforming it from a shared ritual of joy and terror to an individual performance: only one person may ride the roller coaster, Brava!, at a time. Brava!’s single cart emerges from behind a two-story velvet stage curtain, moves across the coaster’s pink tracks, and ultimately comes to rest on the wooden stage, while onlookers observe from below. Visitors can see the roller coaster activated by riders throughout the day.

If you'd like, you can see it in action both from fan videos and official walkthroughs. I'm sure it was a delight to see in person.