At which Philadelphia landmark was the United States Constitution signed on September 17, 1787?

The United States Constitution was signed at Independence Hall on September 17, 1787.

The signing occurred at the Pennsylvania State House in Philadelphia, the building now widely known as Independence Hall. The Constitutional Convention had met there for four months to replace the weak Articles of Confederation with a stronger federal framework. Thirty-nine delegates signed the completed document, representing 12 states; Rhode Island had declined to send delegates.

Independence Hall is also closely associated with the Declaration of Independence, which the Second Continental Congress adopted there in 1776. That connection can cause confusion, because the building served as the setting for both milestones. The Constitution still required ratification by the states before it could take effect, and it became operative after the ninth state, New Hampshire, approved it in June 1788. Philadelphia remained the national capital until the federal government moved to Washington, D.C., in 1800.