The 1787 Constitutional Convention that created the U.S. Constitution took place in Philadelphia.
Delegates met in the Pennsylvania State House, now known as Independence Hall. The convention opened on May 25, 1787, after enough state delegations arrived to form a quorum, and concluded on September 17.
The meeting was originally called to revise the Articles of Confederation, the first national governing framework. Instead, delegates developed an entirely new system with legislative, executive, and judicial branches. George Washington presided, while James Madison’s proposals strongly influenced the discussions.
Philadelphia was also the setting for the Declaration of Independence and the Second Continental Congress. A common mix-up is confusing the convention’s location with the later national capital: the federal government first operated under the Constitution from New York City, then Philadelphia, before moving to Washington, D.C.