In most parking garages, the mystery is figuring out where you parked your car. The delight is remembering. But the 7th Street Parking Garage in Charlotte offers very different mysteries and delights.

“Touch My Building” is an “urban musical instrument” by American sound artist and architect Christopher Janney, who works at the intersection of architecture and music. Some of his pieces are performances, some are installations, but most of them defy easy categorization. Many of them require a human element, like his master’s thesis project “Soundstair,” which uses photoelectric sensors and a sound sampler to make music as a person walks or dances along a set of steps.

“Touch My Building” was designed to encourage pedestrians to take a break and interact with their surroundings. It’s massive in scale, coating nearly the entire exterior of the nine-story parking building. The garage is covered in transparent blue and purple rectangles, connected to 36 30-foot-tall red fins. When the fins are touched, they light up and play music. But the building also has a mind of its own. Different tunes play automatically every hour and a “ghost” in the building will sometimes trigger random performances. (Janney says that this last feature allows the building to properly engage passersby in conversation. It’s saying hello.)

The trickiest, but most rewarding, way to converse with the “ghost” is to solve a puzzle. A plaque mounted on the side of the building lays out a riddle. If you are able to solve it, you get quite the show.