The 1851 Central Park Arsenal, renovated in 1934 from its dilapidated state by New Deal TERA and CWA workers for use as the new consolidated New York City Parks Department headquarters, from a design by Parks Department's newly hired chief architect Aymar Embury II*. You can read about the history of this building in this 2007 New York Times article.

*

Or if not by Embury personally, by someone he supervised. Most accounts credit Embury himself for the design, but they always say "probably" or "almost certainly". Since this building was to be Parks Dept headquarters, I suppose they didn't yet have a place to keep records until they finished renovating it.