Trilithon

A trilithon or trilith is a structure consisting of two large vertical stones supporting a third stone set horizontally across the top. It is commonly used in the context of megalithic monuments. The most famous trilithons are those of Stonehenge in England.

The word trilithon is derived from Greek 'having three stones' and was first used in its modern archaelogical sense by William Stukeley.

Other famous trilithons include those found in the Megalithic temples of Malta, the Osireion in Egypt, and the Haʻamonga ʻa Maui in Tonga, Polynesia. The term is also used to describe the groups of three stones in the Hunebed tombs of the Netherlands.