Marshwood Castle - Credit: Wikimedia Commons
Marshwood Castle was a motte-and-bailey castle in Marshwood, Dorset, within the Vale of Marshwood. It was built by William de Mandeville following his elevation to Baron Marshwood in 1205 by King John, and is first recorded as a built castle in 1215. The castle is no longer standing, but ruins remain and they are a scheduled monument. Read more on Wikipedia
Source: en.wikipedia.org