State of the Art Munitions, 1869

Cannonballs for the 15" Rodman gun at Fort Mason, looking towards Alcatraz, circa 1869. 
Each cannonball weighed 400 pounds.
The canon sitting in the background is a little gun, for show, or perhaps to deter thieves.

Rodman was an ordinance officer who spent several years developing techniques for casting very large guns.
Fort Mason is a former United States Army post on the north side of San Francisco, about half way between the Golden Gate and the Bay bridges. Fort Mason served as an Army post for more than 100 years, initially as a coastal defense site and subsequently as a military port facility. During World War II, it was the principal port for the Pacific campaign. - Wikipedia

Via California Bob.

Update September 2016. Added statement about the little gun.