"Constitution Day commemorates the formation and signing of the U.S. Constitution by thirty-nine brave men on September 17, 1787, recognizing all who, are born in the U.S. or by naturalization, have become citizens." http://www.constitutionday.com.
"The U.S. Constitution established America's national government and fundamental laws, and guaranteed certain basic rights for its citizens." http://www.history.com/topics/constitution. "The United States Constitution is the world's longest surviving written charter of government." http://www.senate.gov/artandhistory/history/common/generic/ConstitutionDay.htm. "Empowered with the sovereign authority of the people by the framers and the consent of the legislatures of the states, it is the source of all government powers, and also provides important limitations on the government that protect the fundamental rights of United States citizens." https://www.whitehouse.gov/1600/constitution.
Fun Constitution Facts:
Signed in 1787, "but it wasn't until 1788 that it was ratified by the necessary nine states." http://constitutioncenter.org/constitution-day/about-constitution-day/10-fast-facts-on-the-constitution/.
"George Washington and James Madison were the only presidents who signed the Constitution." http://www.constitutionfacts.com/us-constitution-amendments/fascinating-facts/.
"For 61 years, from 1804 to 1865, no amendments were added to the Constitution." http://blogs.archives.gov/prologue/?p=10346.
"Only one amendment to the Constitution has been repealed: the 18th (Prohibition)." http://blogs.archives.gov/prologue/?p=10346.
"Since 1952, the Constitution has been on display in the National Archives Building in Washington, DC. Currently, all four pages are displayed behind protective glass framed with titanium. To preserve the parchment's quality, the cases contain argon gas and are kept at 67 degrees Fahrenheit with a relative humidity of 40 percent." http://www.constitutionfacts.com/us-constitution-amendments/fascinating-facts/.
Read the original Constitution of the United States here: http://www.archives.gov/exhibits/charters/constitution.html.