A naturally lit courtyard is an ATRIUM, which is a space with a roof or open to the sky, surrounded by walls or buildings. It is often used as a gathering place and can be found in many public and private buildings. The term comes from the Latin word for 'ENTRYWAY' and is often used to refer to a large, open-air courtyard. The natural light that enters the ATRIUM creates a pleasant atmosphere and can be used to create a beautiful outdoor space.