For decades, Harvard students have gone to Tommy's Lunch on Mt. Auburn Street seeking French fries, lime rickeys and late-night pinball games.

But students arriving there now will find only a sign in the window reading CLOSED. After more than 25 years as a Cambridge institution, Tommy's Lunch is no more.

The restaurant is slated to reopen, under new ownership, as Tommy's House of Pizza in January of next year, according to the sign.

Neither former owner Tommy Stefanos nor the new owners could be reached for comment last night.

But neighboring merchants expressed surprise at the sudden closing.

"They're closed for good?" asked the manager of Pinocchio's Pizza on Winthrop St., who identified himself only as "Ralph Z."

Employees at The Starr Book Shop and Elsie's also on Mount Auburn St., said they had no idea that Tommy's Lunch was folding.

"I was surprised that Tommy's closed so early," said Jan Cooper, an Elsie's worker. Cooper said she had not expected Stefanos to retire for several more years.

Neighborhood merchants say they have no reason to believe the restaurant was in financial straits.

"It's a good location...I don't see how you could go under," said Ralph Z.

Tommy's Lunch, known for its late hours, served grill food, sandwiches and snacks. The restaurant also harbored a collection of pinball and video games, making it a favorite hangout for Cambridge youths.

"Tommy's runs" have been a nightly tradition at The Crimson for the past 20 years, according to Crimson Production Supervisor Patrick R. Sorrento.

Each production night, a Crimson staffer goes to Tommy's to buy coffee for Sorrento and food for other staff members.

"It's been a tradition that the compers always made the Tommy's run," Sorrento said. "That's how they've always been initiated. It's the only place in the Square where you can get good coffee."

Students and Cambridge residents interviewed yesterday said they were sad to see the passing of a local landmark.