Two urban districts, Dongcheng and Xicheng form the urban core of Beijing. They occupy the area inside the old walled city, which used to be divided into two walled sections, "neicheng", the inner city and "waicheng", the adjoining outer city to the south. Though the city walls no longer stand, they continue to retain geographic significance. Streets that once traversed the wall are still named "nei" (inner) or "wai" (outer) in relationship to whether the street section is inside or outside the wall. Today, Line 2 loop of the Beijing Subway traces the inner city wall. The 2nd Ring Road outlines the combined walled city including the outer city.