1836 U.S. Patent Office fire

The location here is Pennsylvania Ave where early records hint at the site of the fire.  But the site is just a temporary location until the exact location of the Blodget's Hotel (where the Patent Office was and where the fire occurred) can be located. 

1836 U.S. Patent Office fire

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.^[2][3]

• http://en.wikipedia.org/wiki/1836 U.S. Patent Office fire