Restormel Castle is situated on the 
River Fowey near 
Lostwithiel.It is one of the four Norman castles of Cornwall, the others being 
Launceston, 
Tintagel and 
Trematon.
It was built in 1100 in the typical 
motte and bailey style and is a perfect example of military architecture of its period, and one of the finest in England. The castle belonged to the Cardinhams in the 12th century, until Andrew de Cardinham's daughter married 
Thomas de Tracey, who owned the castle until 1264, after which it went to 
Simon de Montfort and to 
Henry III's brother, 
Richard of Cornwall. Richard died in 1271, and his son 
Edmund in 1300. From 1337 it became one of the 17 
Antiqua maneria of the 
Duchy of Cornwall.
Restormel Castle is now in the care of 
English Heritage and is open to the public.
The castle was built behind a 17 metre moat, upon slopes which were artificially steepened. Restormel has seen action only once during its long history, when 
Charles I's forces drove out the Parliamentarian garrison during the 
Civil War.
In 1999 members of the 
Cornish Stannary Parliament removed signs from this site and other 
Cornish sites under the care of the 
English Heritage organisation, based upon the claim that the sites should properly be marked as Cornish heritage and not English. Three men later paid criminal fines in connection with these actions. 
In 2007 
British Archaeology magazine reported the discovery of a 
Roman fort near Restormel castle. A 
geophysical magnetometer survey was conducted by members of the 
Saltash Heritage.
(Referances taken from Wikipedia)