How thoughtful that the good burghers of the village have, like those of Avebury, named their hometown after its Neolithic monument. Makes it so much easier to find on the map. More towns should do this.
It's just over 4ft high and nearly 3ft wide at the base, about 1ft thick and aligned with the thin edge facing roughly north-south. The southern side is vertical, and it curves down to the north.
The material is brown and grey, tough and quartzy crystally stuff. It is amazingly jagged and unweathered, and we thought perhaps we'd found something altogether more modern, but the map insisted that this must be the place.
The stone stands 50m or so from the road in a field bounded by a thick hedge. The village of Longstone is basically a crossroads. The stone is found off the road south from the crossroads (signposted Amroth), a few hundred metres along in the first field on your left.
The stone is directly opposite a house called Longstone Manse, although the entrance to the field is a bit further along.
It stands on a north facing slope just as it levels to flat land, looking up to a hill at 147118 which is the high point of the horizon and has 'Fort' marked on the map in olde lettering. These places are often a fort, though sometimes they're ancient ritual enclosures. Even when they are forts, these were sometimes built on top of older ritual enclosures (maybe cos the work's already half done, maybe to add extra imposing meaning by controlling formerly revered ground, maybe both).
There's a probable sightline with Parc y Garreg, the menhir about a mile away on the SE side of that hill.
Visited 8th August 2003: The Longstone sits in a field just south of the village. There's no public footpath to the stone, but when we visited there were no crops in the field, so I wondered in to take a closer look at it.
The stone isn't enormous, but it's pale colouration makes it stand out from a distance. The field is surrounded by relatively tall hedges, so it's almost impossible to spot it from the road. The power lines that run to the north of Longstone village dominate the skyline, and make for a contrasting backdrop to the stone.