The parking lot flanking the Union Station Terminal Annex is gone, and a large data center is rising in its place.

Denver-based CoreSite Realty broke ground earlier this year on the project, which calls for the construction of a four-story, 93-foot-tall building featuring 180,000 square feet of floor area and an adjacent parking garage for 216 vehicles.

Plans call for a contemporary mid-rise structure, clad in board-formed concrete and cement fiber panels.

The ground-up project will be CoreSite's third data center in the Los Angeles area, including an adjacent complex within the historic Terminal Annex Building, once the central mail processing center for Los Angeles.  The other, located in the One Wilshire high-rise in the Financial District, has been called "the most highly-connected internet point in the western U.S."

While both the Terminal Annex and the adjacent site will function as data centers for the foreseeable future, this was not the original vision for either property.  The 1996 Alameda District Specific plan foresaw a 12-story office tower being developed on the parking lot, and the former mail processing center being converted for similar purposes.

A more recent master plan adopted for Union Station is less ambitious and less prescriptive regarding the type of development at the station, though it sets a ceiling of 3.25 million square feet.  However, the current plan also considers capital improvements the transit hub and public realm improvements on surrounding streets.