High Quality Content by WIKIPEDIA articles! The December 15 1836 U.S. Patent Office fire was the first of several disastrous fires the U.S. Patent Office has had in its history. An initial investigation considered the possibility of arson due to suspected corruption in the Post Office, which shared the same building, but it was later ruled out. The cause was ultimately determined to be accidental. This event is considered to be a turning point in the history of the Patent Office.