Castle Dore is an Iron Age hill fort (ringfort) near Fowey in Cornwall, in the United Kingdom located at grid reference SX103548. It was probably occupied from the 5th or 4th centuries BC until the 1st century BC. It consists of two ditches surrounding a circular area 79 metres (259 ft) in diameter. Excavated in the 1930s, it is one of the most intensively investigated Iron Age hillforts in Cornwall.
The perimeter of Castle Dore consists of two ditches (bivallate). The inner ditch is circular, measuring 79 metres (259 ft) in diameter.
Archaeologist Ralegh Radford led excavations at Castle Dore between 1936 and 1937. Five decades later, the work still represented the most intensive investigation of a hillfort in Cornwall. At the time of Radford's work, archaeologists tended to concentrate on the defences in the course of examining hillforts; Radford, however, investigated the interior and found postholes belonging to huts of at least two distinct phases of occupation.