Hosting the parties in her mansion at 350 Fifth Avenue, Mrs. Astor was the ruler of this affluent set.  During her parties, she would often be seen sitting on a red velvet couch, surveying her guests’ behavior.  By the 1880s, these annual balls, always thrown on a Monday in January, were a must-attend event, with the guest list determining who was ‘in’ for the rest of the year.  In 1896, Mrs. Astor's son "Jack" Astor (1864-1912) built a palatial twin residence for himself and his widowed mother at 840 Fifth Avenue where she died in 1908.  Mrs. Astor's original house at 350 Fifth Avenue was replaced by the Waldorf-Astoria Hotel which then was razed in 1929 to build the Empire State Building which became the tallest building in the world at the time.