Mynwent-y-llwyn, 'the burial ground of the grove', is an apparently artificial mound set in the former wetlands of Malltraeth and is said to be the site of a medieval chapel. It is an oval, flat-topped mound about 62m east-west by 50m and 2.6m high, the summit being roughly 37m by 24m. It is said to be composed of clay. A resistivity survey carried out in 1969 indicated the presence of an oval ditch circuit about 30m by 25m. The mound itself appears to be ditched on the aerial coverage.

In 1796 the site was listed as 'Mynwent y llwyn Chapel', however, there is little other indication that this is a chapel site. The form of the monument may be thought suggestive of a ship burial.

Source: RCAHM Anglesey Inventory (1937), 96
Source: White in the Transactions of the Anglesey Antiquarian Society and Field Club for 1971-72, 32-3 note 35

John Wiles, RCAHMW, 7 August 2007