the district is divided into four quadrants of unequal area: northwest (nw), northeast (ne), southeast (se), and southwest (sw). the axes bounding the quadrants radiate from the u.s. capitol building. all road names include the quadrant abbreviation to indicate their location, and house numbers are assigned based on the approximate number of blocks away from the capitol. in most of the city, the streets are set out in a grid pattern with east–west streets named with letters ("e.g.", c street sw) and north–south streets with numbers ("e.g.", 4th street nw). two avenues, constitution avenue and independence avenue, line each side of the mall. many of the diagonal streets and avenues in washington are named after states. some of these streets are particularly noteworthy, such as pennsylvania avenue, which connects the white house with the u.s. capitol and massachusetts avenue, a section of which is informally known as embassy row from the number of foreign embassies located along the street.