1. Monknash Grange (MG 17)
The most impressive surviving remains of a monastic grange in Glamorgan are those at Monknash (Figs.144-6; Pis. 4, 36). The grange came into existence in the earliest years of the Abbey (founded in 1130), from a grant by Richard de Granville.
The basic feature of the surviving remains of the grange (see Fig. 144) is a large quadrangular (or perhaps more correctly pentagonal) enclosure, measuring about 320m along the N.E. side which flanks the Heol Las, the road (on the line of the medieval 'green way') from Marcross to Monknash and on to St. Brides Major; 262m along the S.E. side; 214m along the S.W. side; and 159m and 85m respectively along the two stretches of the slightly angled N.W. side. The area thus enclosed is about 20 acres. The boundary has been destroyed by modern houses and walls along the S.E. side and the S.E. half of the N.E. side, but along the S.W. side and the remainder of the N.E. side it can be traced as a bank (doubled along the S.E. half of the S.W. side) 5-8 m wide and 50-100 cm high, and along the N.W. side as a ditch 5m wide and 1m deep. Within this, the N.W. and S.W. sides remain of a smaller and more strictly rectilinear enclosure, about 152m each way (6 acres), defined by a bank 5-7 m wide and 1 m high with external ditch 6-8 m wide and 60-l00cm deep. Through both enclosures the Nash Brook flows from N.E. to S.W.
22 April 1977.
(Extracted from RCAHMW, Inventory of Ancient Monuments in Glamorgan, Vol. III, Part II, 1982, pp.262-266. )
B.A.Malaws, RCAHMW, 11 September 2001.

2. A Cistercian monastic grange, attached to Neath Abbey, was established at Monknash around 1130 by Richard de Granville and continued until 1533. The visible remains today include a polygonal enclosure, c.350m N-S by 360m, defined by scarps and banks, with remains of sub-divisions and traces of buildings. The ruins of a later barn (NPRN 37614) and grade II listed dovecote (NPRN 37613) also lie on the site.
see Glamorgan Inventory vol.3(2), 262-5.
J.Wiles, RCAHMW, 14 January 2003 (edited)

3. According to a charter of 1140 the early history of the grange may have involved the exchange of the originally granted land (or 140 acres of it) with the lord of Ogmore for a larger area, a gift which also included the site of a mill on the Ewenny River (1) (NPRN 414191). The extent of monastic land hereabouts is shown on Rees's map (2).
(1) A.G.Foster `Two deeds relating to Neath Abbey?, in W.Rees & H.J.Randall (eds.) South Wales and Monmouthshire Record Society, no.2 (1950), pp.201-2.
(2) W.Rees, Map of South Wales & the March in the Fourteenth Century (1932)
David Leighton, RCAHMW, 7 July 2011