In which building was the United States Constitution signed in 1787?

The United States Constitution was signed in Independence Hall in Philadelphia in 1787.

The building was then called the Pennsylvania State House. Delegates met there for the Constitutional Convention from May 25 through September 17, 1787, and thirty-nine delegates signed the completed Constitution on September 17.

The same building had already hosted major events of the American Revolution. The Second Continental Congress adopted the Declaration of Independence there in 1776, and the Articles of Confederation were drafted there. Those connections made the building a central symbol of the founding period.

The name “Independence Hall” became common later, reflecting the building's association with independence. The Constitution was not signed by every convention delegate: several delegates refused or were absent, and three delegates present declined to sign. The document then went to the states for ratification, becoming effective after New Hampshire supplied the ninth ratification in June 1788.