

A boozy farewell party on the roof of a Greenwich Village townhouse ended in tragedy early Sunday when a young woman danced too close to the edge and plunged to the sidewalk in front of passers-by, cops said.

Cindy Yeh, a 23-year-old intern at the Museum of Modern Art, was declared brain-dead at Bellevue Hospital after the four-story fall, law-enforcement sources said.

Doctors were awaiting the arrival of her family from California.

A friend said Yeh, of Bushwick, Brooklyn, had been engaged to be married.

It was unclear whether her fiancé had been at the party on the rooftop at 179 Sullivan St., which was littered with empty bottles of beer, wine and Champagne hours after.

“Last night was their final farewell party on the roof,” the neighbor said.

The party had been hosted by three roommates whose lease on an apartment in the building was almost up, a building resident said.

Yeh had been swaying to music on a sloping part of the roof at the front of the building at about 1:10 a.m. when she lost her footing and fell, law-enforcement sources said.

A man who lives down the block said he was out for a stroll with his wife when Yeh crashed down.

“It was like she just tumbled down and smashed down in front of the building,” the man, 25, said.

“Her friends ran out of the door screaming. A guy held her and yelled out, ‘She’s still breathing!’ ”

“Another guy was crying and punching a car, and then we saw two girls crying while they called 911,” he added.

Another tenant in the building said she saw EMTs treating Yeh on the sidewalk.

“There was a lot of bleeding from her head,” the tenant said.

Several neighbors said the building is notorious for its rowdy roof parties.

“It gets loud up there, and it goes on until late,” said Rene Felio, 25. “Lots of drinking, too, and I am sure roofs and getting drunk are a bad mix.”

Craig Walters, 41, said: “This is a quiet block. The only problem is that building.”

Yeh’s social-media accounts say she was raised in San Jose, Calif., and earned a bachelor’s in communication from the University of California, San Diego, where she studied cinematography and film and video production.

She had been working as a yearlong intern at MoMA after a series of jobs and internships in Los Angeles.

City records show the Sullivan Street building was bought in 1980 by Germano and Marie Henriques.

Marie didn’t answer the buzzer or return a message left at her home on nearby Thompson Street.

Additional reporting by Frank Rosario