Oculus (architecture)

A horizontal oculus in the center of a dome is also called opaion (from Ancient Greek ὀπαῖον '(smoke) hole'; pl.

The term is increasingly used for circular windows (in which case it could also be called an oculus), but not for holes in domes or ceilings.

This type of window can also be found in the late Romanesque period in the area of secular architecture in the castles of Frederick II of Hohenstaufen, Holy Roman Emperor from 1220 to 1250, (Castel del Monte, Palazzo San Gervasio, on the donjon in the castle of Lucera, etc.

[5] Early examples of the oculus in Renaissance architecture can be seen in Florence Cathedral, in the nave clerestory and topping the crowns of the arcade arches.

Widely used by Neo-Palladian architects including Colen Campbell, one can be seen in the dome of Thomas Jefferson's Rotunda at the University of Virginia.