Questions about SF Great Fire (looking for natives)

[Crossroads Inc.]

So in my research of buildings lost during the great SF Fire, I started coming across "Burn Maps" of the city after the fire.

Several of these show an area, in the very heart of the fire, the seemed to go utterly untouched.
On the streets between "Green and Vallejo" and "Jones and Taylor" there seems to be a full city block, and some areas around it, that went untouched.

My question is... What the heck was there?

One would think that anything that survived the Great Fire would have quite of bit of historical significance ot the city. Especially if it survived right in the middle of total devastation.
Today on the site there is nothing more then some residential towers and some small condos.
no historical markers, or museum or even a "This spot survived the Great Fire!!" plack.

So... Any locals or others know what Was there during the fire?