MEXICO CITY (May 6) -- More than 18,000 people stripped down and bared it all in Mexico City's vast main square Sunday for U.S. photographer Spencer Tunick's biggest nude shoot yet.

Standing up to salute, crouching in fetal positions and lying prone on the tiles of the Zocalo plaza, the volunteers formed a sea of flesh that Tunick snapped from balconies and a small crane in the morning light.

"What a moment for the Mexican art scene!" Tunick said in a news conference. "I think all eyes are looking south from the United Sates to Mexico City to see how a country can be free and treat the naked body as art. Not as pornography or as a crime, but with happiness and caring."