Cubellis, a top-earning international architecture and engineering firm headquartered in Boston, has closed.

The 23-year-old firm, which has 12 offices, including one in Dubai, told its employees of the shutdown the day before Thanksgiving, according to the Boston Business Journal, which first reported the news. In 2008, the firm came in 60th out of the U.S.’s 250 most-successful firms, with revenues of $51 million, according to a survey by Architectural Record.

The immediate cause of the closure was Sovereign Bank’s denial of a key line of credit, which made the firm unable to pay the salaries of its 170 employees, according to the Journal, which quoted founder Len Cubellis.

But the general industry-wide collapse also is to blame, according to Tom Bergerson, a principal in the firm’s office in Newport Beach, California, which at its peak had 24 employees. “Clients can’t get the funding to do the projects they want to do,” says Bergerson, adding that, over the last 18 months, his office had not been paid for certain front-end work. Earlier this week, Bergerson said his own job was in limbo, adding that they are “trying to restructure things so we can continue to operate as an independent entity.”

Bergerson explains that Dubai’s current debt crisis, which has the Middle Eastern emirate unable to pay billions of dollars in bills, only exacerbated the problems of Cubellis. The firm was involved in three major retail projects in Dubai, including the 1.3 million-square-foot expansion of the Ibn Battuta Mall.

In the U.S., meanwhile, Cubellis’s fairly diversified project list included college athletic centers, chain restaurants, and apartment buildings, but also numerous shopping centers, “which are not helpful” in this economy, says Frederick Kramer, president of Boston-based firm ADD Inc, which itself shed 50 jobs, from 170 to 120, between 2007 and today.

Kramer says Cubellis’s closing “is devastatingly sad news for the design profession.”

Repeated calls to Len Cubellis’s office and cell phones were unreturned, as was a call to a Sovereign Bank spokeswoman.

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