No city regulatory agency had the authority to review removal of the iconic PNB letters from their 60-year home atop a Center City tower on Sunday, according to city officials.

The removal was announced last Friday, and on Sunday helicopters hovered over Broad and Chestnut Streets, lifting the 16-foot, 11/2-ton letters from the Art Deco high-rise built by the Wanamaker estate in 1930.

The action came so swiftly that it caught many in the preservation and arts community off guard.

"I was surprised to see . . . it was being removed," said Sean Buffington, president of the University of the Arts and chair of the city Art Commission. "I'm not privy to any details, other than what was in the newspaper."

The Art Commission is mandated by the 1951 City Charter to protect the visual landscape of parts of the cityscape. Its approval is required for placement of any signage on South Broad Street. Removal of signs - even signs that represent "part of the fabric of the city," as one bystander put it during the partial removal - are another matter.

(Three of the 12 letters were removed before the action was suspended because of the unexpected fragility of the letters.)

"To simply remove [a sign] would not come to us," said William Burke, the commission's executive director.

The Philadelphia Historical Commission did not have jurisdiction, either. Unlike, for example, the PSFS Building, One South Broad Street is not on the Philadelphia Register of Historic Buildings; if it were, sign removal would have received a full public review.

The "Founder's Bell" in the building tower, however, was designated a historic object in 2000. When the current building owner, Aion Partners of New York, decided to remove the old PNB logo, the historical commission was asked whether that would have any "adverse impact" on the bell, commission executive director Jonathan E. Farnham said in an e-mail this week. The commission staff decided that the bell would be unaffected.

"The Historical Commission has no jurisdiction over the building and its signage," said Farnham.

As far as the city is concerned, the matter was "dealt with appropriately," said Mark McDonald, Mayor Nutter's spokesman.

The lack of jurisdiction, however, is troubling to some in the preservation community.

"Personally, I am upset with any chipping away at the historical fabric," said Penny Balkin Bach, executive director of the Association for Public Art. "You would hope that there would be some public review. What it does point to is the importance of being proactive about what historic elements there are that remain unprotected."

Benjamin Leech, director of advocacy at the Preservation Alliance of Greater Philadelphia, said there were hundreds of buildings that should be on the Philadelphia register but remain unprotected.

"If the building had been designated, this would have been properly vetted and aired," he said. "There is a very large crack, and it fell through."