One additional comment on the article. Like most journalistic writing these days, it's sorta right! The guns weren't cast "near Ft. Pitt" but at Fort Pitt Foundry, which was located in downtown Pittsburgh in what is now the Strip District along the Allegheny! The iron works was established in 1804, and it's first "mil-spec" job was the casting of the cannonballs used by Commodore O.H. Perry in the Battle of Lake Erie in 1813. Also, I hope the group doing the restoration does a bit more research on the actual mass of those tubes....the "2-3 tons" quoted in the article is off by just about 100%! It's an important number to get right when you bring in a crane!
FWIW, Fort Pitt Foundry cast over 60% of the US artillery used in the Civil War, and became the core-business of Carnegie Steel nee US Steel at the turn of the 19th Century!