@ 14-16 inches in diameter .... is a BIG vent/register cover.
Its size n' looks .... make me think it is auto wheel "cover" ..... but not if its cast iron.
But iffen its cast iron it has to be really old ...... because they quit pouring that "intricate" cast iron a long time ago ...... unless its imported from say Mexico, etc. which I seriously doubt. They prefer the "high volume" repros of the old kitchen gadgets, cast iron banks, etc.
Iffen I remember correctly it requires high "phosphorus" cast iron to "pour" those intricate designs.