Where is it?

I guess I am starting my own theme of photos - where is it?  This is in the United States and is from a city I visited a few weeks ago.  It is a famous building of historical sigmificance.  I guess a better question would be what is the historical significance?



If you zoom in on the wall sign it will give you a clue.  The plaque below was on the house across the street.  It also contains a clue.