1776: The Declaration of Independence is signed. It will take 117 years before someone gets around to saying, "Hey, maybe we should preserve this thing."The Declaration of Independence can be fairly said to stand alongside the Magna Carta and Bill of Rights as the most important documents in the history of democracy. Its significance was understood from the moment it was signed, so one is left to wonder why its preservation was ignored for so long. During the Revolutionary War, the Declaration of Independence was rolled up and toted around like a Thomas Bros. map, although, given the vicissitudes of war, that's perhaps understandable. Less understandable is what came later. Water was spilled on it while it was being copied in 1823. Then it was tacked up on the wall at the U.S. Patent Office for about 40 years, where it was subjected to a strong northern light. Finally, the suggestion was made in 1903 that maybe it shouldn't be exposed to sunlight and, oh, by the way, maybe it should be kept dry, too. The latter turned out to be a bad idea because the Declaration, which was written on parchment, actually needs a bit of moisture to keep from cracking. It wasn't until 1951 that the first modern preservation efforts began. The document was sealed inside a bronze, bullet-proof glass case at the National Archives building in Washington, D.C. Humidified helium replaced oxygen to prevent further erosion, and the glass was filtered to cut down on light exposure. Beginning in 1987, using camera equipment developed for the Hubble Space Telescope, preservationists were able to monitor the Declaration for even the most minute signs of fading or flaking ink. The measures proved effective, so much so that the Declaration outlived its original protective case. After undergoing careful inspection for further erosion in 2003, the document was resealed in a titanium casement filled with inert argon gas. Similar preservation techniques are used to protect the Bill of Rights and Constitution. The Declaration of Independence remains on display in the rotunda of the National Archives, where it is seen by roughly 6,000 tourists every day. At night, when the crowds have all gone home, the case is lowered 22 feet into a vault. That's almost as much protection as the French give to Napoleon.Source: History.com