OLD CITY Philadelphia building officials have ordered the developer renovating Old City's Shirt Corner buildings to demolish the early 19th-century row after engineers discovered wide cracks in the walls, indicating that the structures were on the verge of collapse.

The order, issued Jan. 24 by the Department of Licenses and Inspections, means the city will lose an important group of buildings that once served as warehouses and offices for Philadelphia's port, and later became a quirky retail gateway to Old City. L&I says the group of buildings at Third and Market Streets is "imminently dangerous."

Leo Addimando, whose Alterra Property Group was renovating and reconstructing the buildings to accommodate 59 apartments and a CVS store, said he was disappointed but would abide by the decision. He expects to finalize a safety plan with L&I inspectors Tuesday and begin demolition Wednesday.

"I went into this with the intention of saving these buildings," said Addimando, who serves as vice chairman of the Preservation Alliance, an advocacy group. "But I've been convinced that I have no choice."

The cracks and other structural problems were discovered in mid-January while workers were peeling away drywall to prepare for the renovations. After Addimando's engineering firm, Cooke Brown, pointed out the cracks and bulges in the front facades, the developer said, he called in two engineering consultants to assess the situation, Keast & Hood and O'Donnell & Naccarato.

A report issued by Keast & Hood concluded that the buildings were unstable and advised that they be taken down.

Addimando said he planned to build on the original foundations, creating a faithful replica of the 19th-century row. Because the group of buildings was landmarked, the Historical Commission must approve the choice of brick, mortar, and other details.

Had the commission been certain that the old facades were a lost cause, it might have encouraged Addimando to design a more modern-looking replacement.

The buildings, which line the north side of Market Street, have been deteriorating for years, and a previous proposal for the site also involved constructing a facsimile. Addimando was the first developer to attempt to save the structures.

"We've known for 10 or 15 years that these buildings had serious structural problems, but we were so glad that Leo was adventurous enough to try to reconstruct them," said Jon Farnham, the commission's executive director. In the end, he added, "I wasn't surprised at all" that the buildings were too far gone.