The Downs are highest near the Kent-Surrey border, often reaching heights in excess of above sea level at the crest of the escarpment. The highest point is Botley Hill in Surrey at . The County top of Kent at Betsom's Hill, with a height of is located nearby, and the highest point in Greater London, Westerham Heights, at is on the northern side of the same hill. East of the Medway Valley the Downs become broader and flatter, extending as far as the Isle of Thanet.