Known. Stone towers at Axum were carved with fake windows.
Axum is in Ethiopia, on the Horn of Africa. The local Agaw people began to fill and expand the city around 400 BC. By the middle of the 2nd century BC it was a strong kingdom. The kingdom was richest from the 3rd to the 5th centuries AD. Tombs of the wealthy have been found there. Their grave monuments are tall stone towers, also called obelisks, carved with writing from top to bottom. They have stone doors and fake windows. The tallest was about 30 metres high. The largest one broke when it fell.
Historians are not certain what made the kingdom fall.
https://www.ancient-origins.net/ancient-places-africa/axum-legendary-kingdom-ancient-ethiopia-006720