Awaiting the Dimming of G.E. at 30 Rock

Brian Harkin for The New York Times The G.E. sign atop 30 Rockefeller Plaza, as seen from the observation deck of the Empire State Building.

What do the Apollo Theater, Katz’s Delicatessen, the Chelsea Hotel, Pepsi and 30 Rockefeller Plaza have in common

Each business or brand has a recognizable neon sign that presides over New York City. But, as with so many bits of city nostalgia, one of them is endangered.

The New York Times The sign atop the building said R.C.A. for at least 40 years, before it was changed to G.E. (1966 photo).

Comcast announced on Feb. 11 that it would buy the remaining shares of NBCUniversal from General Electric. Included in the sale is NBC’s studios and offices in the G.E. Building, whose address is 30 Rockefeller Plaza.

Naming rights to the building were part of the deal â€" so, in a development presciently satirized by the sitcom “30 Rock,” the huge, crimson General Electric logo adorning the top of the building may soon be no more.

Comcast has yet to announ! ce any plans regarding the sign, but if it removes it, it would be only the latest time the logo at 30 Rockefeller Plaza has changed.

The first sign placed atop the Art Deco building was a yellow R.C.A. logo done in geometric sans serif in 1937, according to Thomas Rinaldi, a blogger and the author of “New York Neon,” a book about vanishing neon signs in the city. The 1937 sign was replaced by another, more futuristic R.C.A. sign in 1969, which gave way to the scarlet General Electric logo during the 1980s.

The disappearance of gaseous rooftop signs has continued inexorably since a change to zoning ordinances in the 1960s made new ones basically illegal, Mr. Rinaldi said. The signs that remain exist because of a loophole that allows them to be replaced by new ones as long as they have existed continuously in the same location.

Replacing the one at 30 Rockefeller Plaza, an oficial landmark, could prove more difficult because it may require approval from the city’s Landmarks Preservation Commission.

Mr. Rinaldi said that, ideally, a new sign would complement the building’s design.

“I think the Comcast logo would look a little incongruous atop an Art Deco skyscraper, though I think the same could be said for the G.E. logo or the ’60s R.C.A. logo,” Mr. Rinaldi said. “It would be best to have a sign up there that matched the character of the building.”

Given the choice, he said, he would opt for a potentially more permanent solution than an ever-changing series of corporate owners. “I think I’d do NBC in the same kind of lettering that was there originally,” Mr. Rinaldi said. “NBC’s been associated with that building since it was built.”

What sign do you think would look best on the roof of 30 Rockefeller Plaza