The Declaration of Independence was adopted in the Pennsylvania State House (Independence Hall), on July 4, 1776. The U.S. Constitution was signed at the same location in September, 1787.
IMAGE: By Captain Albert E. Theberge, NOAA Corps (ret.) - NOAA Photo Library: amer0024, Public Domain, https://commons.wikimedia.org/w/index.php?curid=17995457