Plan view of下沉 courtyard on the first floor of a Western-style villa

Quick answer：

The term '洋房一楼下沉庭院平面图' refers to a plan view of a sunken courtyard located on the first floor of a Western-style villa. This type of architectural feature is common in modern residential design, where a courtyard is partially or fully sunken below ground level. The plan view would typically include dimensions, architectural elements, and the layout of the courtyard in relation to the villa's structure.