Object hidden inside wall of property, are you allowed to keep it?

[Ryan B.]

Say someone happened to purchase an old bank that had been turned into a SFR. Hypothetically speaking, if something happen to be found inside a hollowed out brick in the crawlspace, would they be allowed to keep it?

[Ryan B.]

It is a pretty cool property, all block building with the words "bank" and "1911" inscribed in huge letters on the front. Reminds you of what you would picture in an old west movie. It has two really big walk in closets that used to be the old cement bank vaults.