This is at the corner of Bethel and Merchant. Do you know what it is? Okay, not Erick and Tish shooting. The other thing.
According to author Sheila Sarhangi in her awesome book Honolulu Then and Now (see my previous Old Hawaii post) it's one of two cannons reportedly taken from Fort Honolulu (Fort Honolulu?) which were used by post office visitors as horse-hitching posts!!