Restormel Castle (Cornish: Kastel Rostorrmel)[1] lies by the River Fowey near Lostwithiel in Cornwall, England, UK.

Located on a spur overlooking the River Fowey, Restormel Castle is an unusually well-preserved example of a circular shell keep, a rare type of fortification built during a short period in the 12th and early 13th centuries.

[3] An external bailey wall, apparently constructed of timber with earthwork defences, has since been destroyed, leaving no trace.

[10] Restormel was part of the fiefdom of the Norman magnate Robert, Count of Mortain, located within the manor of Bodardle in the parish of Lanlivery.

[11] Constructed in the middle of a large deer park, the castle overlooked the primary crossing point over the River Fowey, a key tactical location;.

[14] Robert de Cardinham, lord of the manor between 1192 and 1225, built up the inner curtain walls and converted the gatehouse completely to stone, giving the castle its current design.

[18] After some persuasion, Isolda de Cardinham granted the castle to Henry III's brother, Richard of Cornwall in 1270.

[19] Richard died in 1271, and his son Edmund took over Restormel as his main administrative base, building the inner chambers to the castle during his residence there and titling it his "duchy palace".

[7] When the antiquary John Leland saw it in the 16th century, it had fallen into ruin and had been extensively robbed for its stonework; as he put it, "the timber rooted up, the conduit pipes taken away, the roofe made sale of, the planchings rotten, the wals fallen down, and the hewed stones of the windowes, dournes, and clavels, pluct out to serve private buildings; onely there remayneth an utter defacement, to complayne upon this unregarded distresse.

Restormel Manor, now a grade II listed building, is owned by the Duchy of Cornwall and is subdivided into luxury apartments with holiday accommodation in the outbuildings.

[28] Restormel has seen action only once during its long history, when a Parliamentary garrison occupied the ruins and made some basic repairs during the Civil War.

The French writer Henri-François-Alphonse Esquiros, who visited the castle in 1865, described the ruins as forming "what the English call a romantic scene."

[7] In her poetical illustration 'Restormel Castle, Cornwall', to a picture by Thomas Allom, Letitia Elizabeth Landon tells a spooky tale of the death of its last 'castellan or constable', which she states to be 'traditionary'.