Known. Deep layers under the palace hold a long-lived royal city.
In Benin City, Nigeria, the Kingdom of Benin lasted from about 1200 to 1897. Diggers found layers up to three metres deep, with traces of people going back before the 1200s, into the first thousand years AD. Buildings from the 1500s and 1600s follow the same lines as older ones. Pots were set upside down, cowrie shells were sealed inside pots, and chalk was laid out in patterns. Pits from metalworking held charcoal, metal waste and pieces of copper alloy. More than 120,000 bits of pottery were found, with beads, pipes, and plants such as oil palm and millet.
The page says some wall dates are still being tested, and not every building is known for certain.
https://www.ancient-origins.net/news-history-archaeology/benin-city-museum-00102275