This year marks the 50th anniversary of the Guggenheim New York, designed by Frank Lloyd Wright. It's a legendary building, and the cavernous central atrium is one of the most famous spaces in modern architecture. It's also a bit of a blank canvas, only rarely filled out with art or installations. For "Contemplating the Void," a new exhibit opening this Friday, the Guggenheim asked over 200 artists and architects to propose "dream interventions." Here's a sneak peek.

Here: The artist Anish Kapoor --maybe best known for his silvery bean sculpture in Chicago's Millennium Park--proposed a one-shot performance piece, in which he'd pour a river of colored sand from a hole in the roof.

MAD Architects , a Chinese firm headed by Yansong Ma, proposed a diaphanous balloon peaking out of the roof, and cradling a central walkway.

N55, from Denmark, proposed what looks a bit like a huge, modern terrarium. Or perhaps the "Humans" exhibit at the Bronx Zoo, circa 2125, when the apes have assumed control.

The Dutch jokesters MVRDV proposed a big trampoline, spanning the entire void and suspended in mid-air.

Saunders Architecture, out of Norway, proposed a swampy forest floor. That figure you see is none other than Frank Lloyd Wright--himself famous for integrating nature into architecture in his masterpiece, Falling Water.

Sometimes, the simplest acts are the most poetic. Artist Alyson Shotz proposed a delicate hanging that would quietly rustle in the air.

Another forest concept, created by West 8, an avant-garde landscape architecture firm based in the Netherlands.

Julien De Smedt Architects , based in Brussels, proposed a spiraling net structure that would allow you to bounce and slide from the top to the museum, all the way to the bottom.