Here's the scoop from the Associated Press.
The Photographer is Spencer Tunick
AMSTERDAM, Netherlands (AP) — Dozens of women posed naked on their bicycles on a bridge over one of Amsterdam's historic canals Sunday — a unique sight even in a city famed for its relaxed attitude toward nudity and sex.
They were among 2,000 men and women who participated in a series of four nude group photos in the city in the early hours of the morning as part of the latest project of U.S. photographer Spencer Tunick.
The first and largest composition was in a decidedly prosaic location: a parking garage on the outer ring of the city.
But what the location lacked in romance, it made up for in style. Participants lined the railings of the garage's twin circular towers, creating a pattern of multicolor stripes against the white building and an overcast sky.
"It was very hard to find space in a city meant for such a small amount of people," Tunick said. "I was very lucky to get almost 2,000 to fill a massive car park."