A hillock or knoll is a small hill, usually separated from a larger group of hills such as a range. Hillocks are similar in their distribution and size to small mesas or buttes. The term is largely a British one. This particular formation occurs often in Great Britain and China. One of the most famous knolls is the one near John F. Kennedy's point of assassination, the Grassy Knoll. A "Blind Knoll" is either hidden or not readily apparent to those driving vehicles. There are road signs that warn of this, advising drivers to slow down.