Yours truly in front of a 15 inch Rodman cannon at Rock Island Arsenal.
This gun was primarily used on land fortifications and larger warships during the civil war. My foot is on the shot fired by this beast, and yes, it was loose, I was able to roll it around! The shot weighs around 250 pounds and is solid. The cannon itself weighs 15 tons!

This gun was made in 1864, and last used around 1895 at who knows what fortification. This particular gun is at the foot of the grave of General Thomas Rodman,(1816-1871) inventor of the weapon, plus the architect of Rock Island Arsenal, dying just before its opening.