Here is a California Landmark plaque for the Bella Union Hotel that is located across Main Street from the 1940 Federal Building. I took the picture during my visit to City Hall this past July 10. Unfortunately, I was facing in the direction of the sun, so the photo came out rather poorly. I will attempt a transcription:
"Near this spot stood the Bella Union Hotel, long a social and political center. Here on October 7, 1858, the first Butterfield Overland mail stage from the east arrived 21 days after leaving St. Louis. Warren Hall was driver and Waterman _rmsby, reporter, the only through passenger."
I think it's funny how the best they could do is say it was "near this spot," rather than "on this spot." Even the historians back then weren't entirely sure where this landmark once stood!
-Scott