Adam Subber, with Cresa Partners in Boston, tells GlobeSt.com that Englewood, CO-based CSG Systems renegotiated the terms of its lease at the two-building, 650,000-sf , class A office park in one of the first significant transactions since the property was purchased by Rreef in January.

"CSG evaluated the market heavily but we were able to retain the top two floors of what is arguably one of the finest buildings on the market and reduce our rent," Subber says. Terms of the lease were not released but he says rents in the building are in the low to mid-$30 per sf price range.

The company, which had been in the building for about 10 years, had been slowly subleasing its former space as it downsized its operation.

Riverfront Office Park, in East Cambridge, won recognition from the city last year for its recycling and energy conservation efforts. The property, which counts the Shaw Group and New England Pension Consultants among its tenants, features amenities that include underground parking, a fitness center, deli and conference center.

Subber, along with Dan Sullivan and Chris Crooks, also with Cresa Partners, represented the tenant. Mark Winters and Dave Townsend from Cushman & Wakefield handled the negotiations for the landlord.