Castell Dyffryn Mawr
                Has been described as a Possible Timber Castle (Ringwork), and also as a Possible Masonry Castle
                There are earthwork remains
                
	
		| Name | Castell Dyffryn Mawr | 
	
		| Alternative Names | Llanfair Nant Gwyn; Parc y Domen | 
	
		| Historic Country | Pembrokeshire | 
	
		| Modern Authority | Pembrokeshire | 
	
		| 1974 Authority | Dyfed | 
	
		| Community | Crymych | 
	
                Ringwork, walled in stone slabs, probably laid in clay or poor mortar. No known history. (King)
A probable castle mound, subsequently modified as a landscape feature: a circular ditched mound, some 20m in diameter, rising 5.5m from base of the generally 3.0m deep ditch; the dished summit of the mound is defined by a roughly 1.6m wide stony bank: a recent bank, some 45m in diameter, surrounds the work, OS County series (Pembroke. XI.4 1889) portraying this bank as tree-planted, with a conifer(s?)on the mound. (Coflien)
This is a fine Norman mound ..., about 50 yards to the south-east of Dyffryn Mawr farm-house. It rises to a height of over 20 feet from the bottom of the surrounding ditch. The centre of the summit, which is 60 feet in diameter, has a saucer-like depression of some 10 feet. Around this basin are the stone foundations (5.5 feet wide) of what was probably the turret of an early manor house. The ditch is 8 feet wide and 10 feet deep ; the counterscarp is crowned with a thick quickset hedge. There are no signs of a bailey. The field on which the mound stands is still known as Pare y domen (Tithe Schedule, No. 357). In the spring of 1920 a narrow trench was driven into the west side of the mound, revealing two-post holes, each about one foot square, in the hard soil just outside the stone foundations. At the foot of each hole was a bed of decayed timber a foot thick. (RCAHMW)
                
                This site is a scheduled monument protected by law
                Not Listed
                
                
                
                
                
                
                The National Monument Record (Coflein) number(s)
                
                County Historic Environment Record
                
                
	
		| OS Map Grid Reference | SN174351 | 
	
		| Latitude | 51.9848899841309 | 
	
		| Longitude | -4.65930986404419 | 
	
		| Eastings | 217480 | 
	
		| Northings | 235170 |