The borough is the largest in Greater London by area and occupies . The majority of the borough is Metropolitan Green Belt, including nearly all of the land south of the A232-A21 route between West Wickham and Pratts Bottom. Consequently, it is also perhaps the most rural borough and contains more of the North Downs than any other, as that escarpment is broad between Bromley and Banstead. This is also reflected in its population density, which is the lowest of the 32 London boroughs.