No doubt you’ve heard about a little something that Mayor Bloomberg is cooking up to lure tourists to the South Street Seaport this summer: a series of 60- to 70-foot-high mechanical waterfalls that will gush from the East River underneath the Brooklyn Bridge. The biggest public art project since The Gates, the piece is the brainchild of artist Olafur Eliasson. The 40-year-old Danish-Icelandic artist is no stranger to churning out the art-world equivalent of Broadway musicals or Hollywood blockbusters: He conjured an artificial sun for the cavernous Turbine Hall of London’s Tate Modern last year. But the East River waterworks are only part of the bill. They’ve been commissioned to coincide with a 15-year retrospective of the artist’s work that’s being mounted by MoMA and P.S.1. Titled “Take Your Time: Olafur Eliasson,” the show promises a sizable “wow” factor, especially from the centerpiece installation, likewise titled Take Your Time. A brand-new work designed for P.S.1., it will feature a giant circular mirror spinning above museumgoers’ heads. Apr 20–Jun 30

One side of the mirror is actually lower than the other. “Because the mirror is tilted six degrees, the reflection of the space is geometrically off—the walls and the floor are slanting,” explains Eliasson. “And as the mirror spins around, one side of the room goes up while the other goes down. It’s constantly tilting around, like a sailboat.” As for the effect on the viewer, he adds, “It takes your sense of balance off for a while. You’re forced to constantly recompose your orientation in this space.”

The 605-pound mirror is made of polished-aluminum aircraft skin stretched over a frame and will take five days to assemble. It completes one full revolution per minute using a motor that the artist found lying around his Berlin studio. Eliasson points out that because of the mirror’s size, a single rpm is pretty fast: “You’ll have to walk quickly to keep up with a spot on its edge.”

The spinning mirror measures nearly 40 feet across—almost the same width as the room. “What was interesting to me was this idea that a spinning mirror is like a paradox,” Eliasson explains. “If you hold one up in front of you and spin it, your reflection doesn’t go around.”