Although Caer Leb is a bit eroded and silted up it’s still worth a look. A roughly square site with a lone stone stump just off centre.
I’ve read that Caer Leb was first thought to be a Medieval moated site but after excavations Roman coins were found so it was then attributed to them instead. Now after excavations at a similar site at Llansadwrn have shown it to be 2nd Century BC, Caer Leb is now thought to be originally Iron Age, and used at various times through the centuries.