399 Park Avenue is a 41-story office building that from 1961 to 2015 was the world headquarters of Citigroup in Manhattan, New York City. The company moved into the building from 55 Wall Street in 1961, and from there to 388 Greenwich Street in 2015.
399 Park Avenue occupies the entire block between Park Avenue and Lexington Avenue and 53rd Street and 54th Street. The building lot was assembled by Vincent Astor who initially planned to build a 46-story Astor Plaza on the site. Astor had problems completing the assembly of the lots of mostly residential buildings as a pharmacy held out.
In 1974, the company opened the Citigroup Center annex across Lexington to the east. In 1987, Citigroup sold one third of its interest in the building along with two-thirds of its interest in Citigroup Center to Dai-Ichi Mutual Life Insurance Company for $670 million. At the time, Citigroup said it was moving many of its offices to a new tower in Long Island City in Queens. Citigroup moved out of the top two thirds of the building but kept the lower floors. Citigroup later bought back its interest in the building.
In 2002, Boston Properties bought the building for $1.06 billion, or $630 square foot, which was the highest price ever paid for an office building at the time. Boston also bought Citigroup Center. Citigroup leased its headquarters from Boston Properties. Citigroup's current lease on the building is set to expire in 2017. In December 2013, Citigroup announced it will relocate its global headquarters to 388 and 390 Greenwich Street in Tribeca, a complex it currently occupies and had owned until 2007, when it sold the building to SL Green Realty.