Plan view of a sunken courtyard

Quick answer：

A sunken courtyard, also known as a sunken garden, is a type of garden design where the garden is lower in elevation than the surrounding area. It creates a sense of intimacy and seclusion. In a plan view, it would be depicted as a closed, enclosed space surrounded by higher ground or walls, with pathways, plants, and sometimes water features. This design can be found in various architectural styles and is particularly popular in traditional Chinese gardens.