One local broker tells GlobeSt.com that the building's mortgage may be what is for sale. "The word on the street is that Teachers [Insurance and Annuity Association] may be looking to finance out of the deal," he says. Unconfirmed reports speculate that Chiofaro Co. could be interested in buying out Teachers.

"There have been a number of Downtown towers traded in the last three or four months," another local broker tells GlobeSt.com. "A lot of our clients are being approached on an unsolicited basis." Clarion Partners recently sold One Federal St. for $375 million to Jamestown, a German real estate firm.

As the broker points out, Boston is one of the few relatively stable markets left. "People are focused on central business districts," he says. "Very few people are buying out in the suburbs or in Cambridge now. There is a flight to quality and a flight to credit. Downtown here does not have too much high tech." Despite an uncertain economy, International Place, which was developed by local developers Donald Chiofaro and Ted Oatis, is also close to the Central Artery, which is going underground as part of the Big Dig.