The Tregiffian Burial Chamber is a Neolithic or early Bronze Age chambered tomb. It is a rare form of a passage grave, known as an Entrance grave. It has an entrance passage, lined with stone slabs, which leads into a central chamber. This type of tomb is also found in the neighbouring Isles of Scilly.
The large stone grave, half of which was covered by a road in 1846, was, unlike Cornish quoits, for the most part covered with soil, with only the entrance exposed. From the edge of the site a passage, covered by four 3 m long stones, led to the 4-metre deep grave chamber. In front of the chamber, a cross-lying ornate stone, with cup-and-ring markings, formed a barrier. The original stone is in Truro, in the Royal Cornwall Museum, the local stone is a replica. Inside the tomb there was the chamber grave, which consisted of upright stones and a cover slab. Tregiffian probably formed a holy place with the Merry Maidens and other sites.
References:The Broch of Clickimin is a large and well preserved, though somewhat restored broch near Lerwick. Originally built on an island in Clickimin Loch (now increased in size by silting and drainage), it was approached by a stone causeway. The water-level in the loch was reduced in 1874, leaving the broch high and dry. The broch is situated within a walled enclosure and, unusually for brochs, features a large 'blockhouse' between the opening in the enclosure and the broch itself. Another unusual feature is a stone slab featuring sculptured footprints, located in the causeway which approached the site. Situated across the loch is the Clickimin Leisure Centre.