下沉庭院效果 on the ground floor

Quick answer：

A sunken courtyard on the ground floor refers to a courtyard or garden that is below the level of the surrounding ground. This architectural feature can create a sense of privacy and intimacy within the building. It is often used in residential or commercial buildings to enhance the aesthetic appeal and functionality of the space. The design considerations include waterproofing, drainage, and structural stability to ensure the safety and longevity of the sunken courtyard.