Porth Hellick Down is an area of downland

Downland

A downland is an area of open chalk hills. This term is especially used to describe the chalk countryside in southern England. Areas of downland are often referred to as Downs....

 on the east side of the island of St Mary's in the Isles of Scilly

Isles of Scilly

The Isles of Scilly form an archipelago off the southwestern tip of the Cornish peninsula of Great Britain. The islands have had a unitary authority council since 1890, and are separate from the Cornwall unitary authority, but some services are combined with Cornwall and the islands are still part...

.

Seven Scillonian entrance grave

Scillonian entrance grave

The entrance graves of Cornwall and the Isles of Scilly, and south east Ireland are megalithic chamber tombs of the Neolithic and early Bronze Age in the British Isles. Comparable sites are also known in Brittany and the Channel Islands...

s stand on the down in a general state of decay. The largest is the Great Tomb which has a 12m diameter and a central burial chamber 3m long and 1m high. An unroofed passage 4.2m long leads into the chamber at an angle. An encircling peristalith

Megalithic architectural elements

This article describes several characteristic architectural elements typical of European megalithic structures.-Forecourt:In archaeology, a forecourt is the name given to the area in front of certain types of chamber tomb...

 was destroyed during misguided restoration work by the Ministry of Works.