What did Philadelphia use to be called? Philadelphia was once the capital of the United States, serving as host for the Constitutional Convention that created the federal constitution in 1787 and being elected capital between 1790 and 1800. Philadelphia gave rise to several lasting institutions such as the American Philosophical Society, Library Company of Philadelphia, Pennsylvania Hospital, and College of Philadelphia - not to mention notable private and public buildings like City Hall and Independence Hall, which served as hubs of commerce and shipping activity during its heydays.