Yesterday, when Landmark Theatres signed deeds and leases to acquire the operations of the Ritz Theaters in Philadelphia, it changed the locks at the Ritz at the Bourse, Ritz East and Ritz Five, and little else.

"Same name. Same movies. Same ticket prices," said Bill Banowsky, chief executive officer of the art-house circuit that now has 59 theaters in 23 prime markets.

"We will customize programming for this market, we will keep the suggestion box, we will make no substantive changes," Banowsky promised. "These theaters are important Philadelphia institutions."

"Business as usual," said a Ritz Five employee who asked not to be identified. "People are buying tickets for and just as they were yesterday."

Both Posel Management, which sold the Ritz Five and transferred leases on the other theaters, and Landmark declined to comment on the price of the transaction.

"We're really excited to be in Philadelphia," Banowsky said by telephone from Dallas. "Before today it was the only one of the top 10 markets we weren't in. Philadelphia is an important step in our evolution."

With operations in cities as diverse as Los Angeles, Denver and Washington, Landmark is "the gold standard," according to Tom Bernard, co-president of Sony Pictures Classics.

"Every market is different in terms of what product works," said Banowsky. "What's effective in Houston and New Orleans doesn't necessarily fly in New York and Los Angeles."

"For the most part, Philadelphia has shown itself to be a sophisticated market like New York," receptive to a mix of foreign, independent and nonfiction films. Landmark was keen on the Ritzes, Banowsky said, because Ramon Posel, the Ritzes' founder, developed programming that had a fanatical following. Posel died in 2005.

While Landmark plans to retain the theaters' names, programming and monthly Ritz Filmbill (which Banowsky said he liked so much that "we might want to replicate it in other markets"), some change is inevitable. And some would be welcomed.

At least two of the 12 Ritz screens will be outfitted for digital projection. That would give Landmark the ability to host events such as Metropolitan Opera simulcasts and the annual screening of Oscar-nominated shorts. As part of regular maintenance, sound and seating improvements would be made.

The most radical change might be at the concessions stand, Banowsky said: "We have a contract with Coca-Cola, so Mr. Pibb will replace Dr. Pepper."

The Ritz 16 in Voorhees was not part of Landmark's acquisition. According to one person close to the negotiations, a deal for the Voorhees operation is in the works with a chain that "would be sensitive to the current mix of mainstream and art-house fare."

The sale of the Ritzes comes at a volatile moment in movie exhibition. Theater owners worry that moviegoers are abandoning the big screen for movies on demandLandmark is a holding of Todd Wagner and Mark Cuban, multimedia entrepreneurs who in 2006 pioneered the simultaneous release of a movie on pay-per-view, on DVD, and in theaters.

Landmark, like the Muvico chain, is betting that good movies and better concessions will continue to draw customers.

"Landmark is open to the idea that the Philadelphia market is large enough to support more screens," said Banowsky, who would not comment on whether the company was looking at other sites in the region.

Rival chains are. Both Muvico and National Amusements, which owns the Bridge in West Philadelphia, are building or scouting locations in the area.

While film fans do not have to say goodbye to the Ritz, they must say "au revoir" to the bust of the French film icon Jeanne Moreau that graced the lobby of the Ritz Five.

The bust has left the building, in the hands of Posel's widow, Dorothy. But concession-stand habitues can breathe a collective sigh of relief. The Toblerone bars remain.