SAN FRANCISCO-Digital Realty Trust Inc. has paid $85 million for a 155,000-square-foot data center in downtown San Francisco. The announcement of the Bay Area deal coincides with the purchase of a similar building in Atlanta, near the Hartsfield-Jackson Atlanta International Airport, for $63 million.

Digital Realty’s new San Francisco building has at least one obvious appeal to the publicly-traded real estate company: The data center, which is a fully leased, multi-tenant building, sits back-to-backwith the company’s existing "server farm" at 365 Main St.

The purchase gives the company a greater "critical mass" in telecommunications and colocator space in San Francisco, according to Digital Realty vice president Pamela Garibaldi. With the purchase of 360 Spear, the company currently has three telecom properties in the city, including 200 Paul. "There's very limited data center space in San Francico," she adds.