399 Park Avenue is a 41-story office building that is the world headquarters of Citigroup in Manhattan, New York City. Citigroup's chairman and chief executive officer operate from the building's second floor. The company moved to the building from 55 Wall Street; a move that marked a migration of several large banks from lower to midtown Manhattan. It 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.