[[Image:Heart Mengustone.jpeg|thumb|left|400px|alt=Mengu Stone Plaque|Mengu Stone Plaque St Austell]]Now embedded in the ground at the foot of the Parish Church tower, the Mengu Stone was once the only antiquity found outside the churchyard in St. Austell.
It is a large piece of dark-coloured stone, possibly schorl or originating from Catacleuse Quarry on the cliffs near Padstow, and it measures approximately 3’ 6” (1050mm) x 3’ (900mm) x 10” (250mm). The Mengu Stone has marked an important site in the town for many centuries and has been mentioned by a number of early historians and travellers. Stones marking boundaries are well documented in Anglo Saxon charters and this could be the case here. The Mengu Stone has always been noted as marking the boundary point of the three manors of Trenance, Treverbyn and Tewington listed in the Domesday Survey. St. Austell as a settlement did not exist in 1086 – only the manor lands were recorded. The name of the first settlement here was Trenance or Trenance Austol.
As a stone marker of importance, the Mengu Stone was used as a site where important news was relayed and proclamations and announcements made. Straying livestock, impounded in the area near the church, would be sold from the Mengu Stone if not claimed after a certain number of market days. John Wesley was said to have preached from this spot.
In 1893, this large, flat, stone was removed from its original position at the junction by the church where the principal streets met, so that it would no longer be in the wheel tracks of vehicles which were fast wearing it away. It was reset on the corner of Fore Street and Menacuddle Street, as near as possible to its original resting place, in the footway alongside the premises now occupied by the Alliance and Leicester Building Society.
In 1971, when it became known that the block of buildings at the eastern end of Fore Street was to be demolished, St. Austell Old Cornwall Society liased with St. Austell Urban District Council to ensure the safety of the Mengu Stone. Mr. Edward Blight, a Vice President of the Society, was present on 18th November, 1971 when the stone was lifted. It was subsequently repositioned at the foot of the south western side of the church tower where it can be seen today. A descriptive plaque is fixed on the wall of the church above the stone.
The Mengu Stone is certainly a piece of St. Austell’s ancient history – what stories it could tell if it were able to speak.