Hines joins the California Public Employees Retirement System(Calpers) in acquiring One and 101 Main St. from Blackstone RealEstate Advisors.

"It's a significant [complex] in a fantastic market," says Hinesvice president David Perry. While acknowledging that the deal hasclosed, Perry declined to provide details, citing an ongoingconfidentiality agreement. He adds that a press release will beissued within a few days on the purchase of the complex, which isalso known as the Riverfront Office Park. Calls to Calpers and NewYork-based Blackstone were not returned by press deadline.

Despite that, industry sources estimate that the buildings soldfor about $325 per sf, or in the $215 million range for the667,000-sf complex. If accurate, that would reportedly be a newrecord for class A office space in Cambridge, which has been apopular target among investors given the city's tight vacancy rateand rents that now average above $50 per sf. At present, forexample, Beacon Capital Partners is entertaining offers from buyersangling to acquire its Technology Square office development a fewblocks from the Riverfront site, while several other Cambridgeoffice buildings have already changed hands this year.