If Gilligan and the Professor ever decided to build a roller coaster, it would probably look something like the chaotic, bamboo structure that is currently sprouting on the roof of the Metropolitan Museum of Art. Begun in March, this ever-evolving assemblage of more than 5,000 interlocking bamboo poles, held together by more than 50 miles of nylon rope, has been continuously gaining height over the last five months. This week, it gains a new foot path along its eastern edge, climbing a staggering 40 feet over the museum's roof.

Produced by the twin-brother artist team of Doug and Mike Starn, who hail from Beacon, N.Y., "Big Bambú," as the structure is called, is one of those rare public sculptures that you can touch and step on, while developing a mild case of vertigo. Though, to be certain, climbing the piece is not nearly as scary as reading the list of instructions that goes with it. (This is the sort of public art that is no doubt keeping battalions of lawyers in designer suits.)

While not the first work of bamboo art you can climb in the city (last year, artist Huang Yong Ping had a coiling bamboo tower at Barbara Gladstone Gallery), "Big Bambú" is certainly the most extravagant — a curving stick wave with criss-crossing walkways that covers almost the entire roof of the museum in a disorderly, organic mass. It is an interesting departure from the Met's typical roof garden installations, which generally stick to neatly-composed works that serve as attractive backdrop to photogenic Manhattanites clutching martinis. Not that the Met has completely dispensed with martinis. For a mere $12, interested parties can acquire the Big Bambú martini, crafted with vodka and infused with Oolong tea. (Tip: Save the drink for after your guided tour of the piece. No one who is even slightly schnockered is allowed to climb the structure.)

How does the whole thing work as art? Well, it's fun, if slightly overwrought. (Okay, a lot overwrought.) There is also something deeply satisfying to the Robinson Crusoe inside of me to be able to admire the expanse of New York City's concrete towers from a creaking, swaying bamboo perch. Man may build his monuments. But nature somehow prevails.

"Big Bambú" is on view at the Met through Oct. 31.