The Tent of Tomorrow and the three observation towers, which were built for the 1964 World's Fair, were named a "National Treasure" by the National Trust for Historic Preservation on Tuesday, the 50th anniversary of the event.
The attraction drew massive lines Tuesday when it was open for a few hours in honor of the fair's anniversary.
The Philip Johnson-designed structures have fallen into decay from decades of neglect, despite pushes from grassroots groups to restore them.
The commitment from the National Trust will bring exposure on a national level and could connect the structures with corporations and other philanthropists interested in restoring the site.
A board member on the trust, Pulitzer-Prize winning architecture critic Paul Goldberger, said the Pavilion would require costly, time-consuming reconstruction — but it would be worth it.
"It's the most exciting, beautiful, and important thing that came out of the 1964 World's Fair," he said.
"It has been for 50 years a landmark at one of the most important intersections of Queens — seen not only residents of Queens but by people from all over because it's on two key roadways."
The Parks Department had estimated in recent studies that it could cost $52 million to fully restore the pavilion and $43 million to restore it without public access.
A complete demolition of the structures would cost $14 million.
Even as the pavilion rusted, Goldberger said it's remained an "iconic structure," and "one of the most beautiful modern compositions I've ever seen."
The state of the pavilion didn't deter hundreds of fans and former fair-goers, who lined up for hours to wear hardhats and get a quick glimpse inside the New York State Pavilion, which is rarely open to the public.
The line stretched over the Grand Central Parkway and into Corona, and the first on the line, Tom Robinson, 55, said he got to the park at 6 a.m. to claim his spot.
The Lindenhurst, LI, native had fond memories of visiting the fair as a kid, and said it was like a homecoming.
"We had the world at out fingertips," he said, rattling off the list of his favorite features — from the Florida Pavilion, which featured a dolphin show, to the new Shea Stadium, which was built across the park.
Marc Cutler, 66, wore an original pin from the fair and recalled taking a public bus from his home in Canarsie on the first day it opened. He visited the fair 12 times.
HIs favorite stop was the Hollywood Pavilion, which featured sets from "West Side Story," "The Ten Commandments" and more, he said.
"It was like a great adventure, really," he said. "It brings back good memories and happiness."