KYLE O'CONNOR, 21, a Drexel University computer-engineering student, was expecting to pick up a textbook he needed for class. "I kind of need it right now," he said. "But, oh well."

O'Connor was one in a steady, daylong flow of people yesterday confused to find that Philadelphia's massive and ornate main post office, on Market Street across from 30th Street Station, had closed for good after 73 years.

The University of Pennsylvania, which bought the building for $28 million, announced last year that it would collaborate with Brandywine Realty Trust to redevelop it. The Internal Revenue Service is to make the building its Philadelphia headquarters beginning in 2010.

The building, a national historic site, served its last postal customers on Friday and was closed to make way for a new post office around the corner, at 30th and Chestnut streets, which opens to the public at 8 a.m. today.

"I don't know if [the new post office] will be any different, more or less," said O'Connor, of Allentown. "It's only an inconvenience right now."

Yesterday, customers were directed to head across the street to the small post office inside 30th Street Station, which is usually closed on Sundays, for makeshift retail services until the new post office opened.

"It was a 30-minute wait," said Pat Cronin, 46, of Haddonfield, N.J., as he left the station's post office. "Over there [at the old post office], they used to have three or four windows, and the wait would be 10 or 15 minutes."

Cronin said that because the old building, built in 1935, was dated, he wasn't surprised to learn that it had closed.

"I was stunned," said Dennis Gemmell, 63, who made an hour trek from Clarksburg, N.J., to have mail sent overnight, as he waited in line at 30th Street Station. "[The post office] was always a dependable place to come in a crisis."

Gemmell, who grew up in Philadelphia, said he'd been coming to the post office for 30 or 40 years.

Sam Wister, a postal police officer who spent much of yesterday morning standing in front of the old post office directing customers across the street, said that people were not taking the change well.

"This is a landmark," he said. "The new building is kind of bland. Nothing fancy."

He said that at one point, someone even tore the yellow caution tape that stretched across the front stairs near the entrance of the old building.

"People are just like, 'No, this can't be closed,' " he said.

Sarita Jordan, 39, traveled from Germantown yesterday to drop someone off at the train station, and said she thought she could kill two birds with one stone and drop her mail off as well.

"I'm a little disappointed, but I see that the other facility [inside the train station] is open," she said, adding that she thought the new building would be inconvenient because it's not on "a main thoroughfare."

Customers aren't the only ones who will feel the effects of the post office's move.

John Lyman, who owns the Auntie Anne's pretzel stand in 30th Street Station, said business owners in the area would be affected, too.

"I'm disappointed in the closing, because with them moving jobs out of there, it will affect our business," said Lyman, 64, who has owned his stand for the last nine years. "I'm hoping in the short term it's negative, but in the long term it's positive."

The sprawling post office, visible from the customer-service lobby of the new building, has a darker interior with wood-paneled ceilings and bronze-gilded post-office boxes, a stark contrast to the bright, modern interior of the new complex.

"Everything here is designed for customer ease-of-use," said U.S. Postal Service customer-service manager James Averitte. "Two regular customers came in yesterday and were very impressed with the look of the building. It's something to be proud of."

Averitte said the new facility is set up to make the flow of mail easier and that the old five-story building was no longer needed because processing and distribution were moved to Lindbergh Boulevard in Southwest Philly.

"This building is set up as a delivery unit," he said. "In the other one, mail wandered. [Here, there is] a better process for carrier operation."

The new building offers a 24-hour lobby for access to about 3,400 post-office boxes, a passport office and retail-service hours seven days a week.

Averitte said that the hours would be cut down slightly at the new location: It will be open 8 a.m. to 9 p.m. Mondays through Saturdays, and 11 a.m. to 7 p.m. Sundays.

This morning, a flag-lowering ceremony was to be held at the old building, followed by a flag-raising ceremony at the new location.

Averitte said he's looking forward to the opening of the new building, but he can't deny the history hidden behind the walls of the old facility.

"It's a grand old building," he said. "I'd love to hear the stories the walls would tell if they could talk."