The Smithsonian Institution plans to move its headquarters from its historic Smithsonian Castle into an office building about a half-mile away.

The institution plans to acquire the building at 600 Maryland Ave. SW from Boston Properties, and its board voted Monday to approve the deal, the Washington Business Journal reports.

The parties did not disclose the terms of the deal, but the 632K SF office building is assessed at roughly $372M. Smithsonian already occupies about 230K SF in the building under a lease with Boston Properties set to expire next year.

The building at 600 Maryland Ave. SW sits next to the L'Enfant Plaza Metro station, one block south of the National Mall. Branded as Capital Gallery, the building was constructed in 1981 and expanded in 2006. It includes two towers of eight and 10 stories, a three-level atrium and a landscaped plaza. The building's ground-floor retail includes Starbucks, Cosmo Cafe, Rice Bar and Vie de France.

The headquarters shift, which has been in the works for several years, will make way for the $650M first phase of renovations planned for its 17-acre South Mall campus. The overall improvements to that campus, which include the historic castle, are expected to cost $2B and take 10 to 20 years.