The 14-story structures are the 155,000-sf Biewend Building and the 98,000-sf Tupper Building. The well-located properties are used as medical laboratory, office and treatment space, housing such operations as TNE's administrative functions, the New England Eye Center and the Adult Orthopedic Clinic. All but two floors of the Tupper Building are used for lab functions, considered among the most attractive product types in the current CRE climate.

"We had a significant amount of interest," Grubb & Ellis Co. broker Philip Giunta tells GlobeSt.com, but Triple Net, based in Santa Ana, CA, beat out the cadre of local and national suitors. Giunta, who represented the sellers, declined to discuss specifics of the deal, as did officials from Triple Net beyond unveiling the 10-year leaseback provision. According to information provided to GlobeSt.com, however, the Biewend Building traded for $54.9 million, whereas the Tupper Building fetched $61.1 million.

TNE has had a presence in Downtown Boston for decades. The medical giant has owned 15 Kneeland St. and 260 Tremont St. since the 1980s, and will continue to occupy all of the space as part of its 10-year leaseback arrangement. Both buildings date to 1924 and were overhauled in 1985 to accommodate the office/research requirements. The assets are located near the city's Chinatown and Theater Districts, areas enjoying substantial investment and new construction of residential, office and hotel product.