A Pictish stone is a type of monumental stele, generally carved or incised with symbols or designs. A few have ogham inscriptions. Located in Scotland, mostly north of the Clyde-Forth line and on the Eastern side of the country, these stones are the most visible remaining evidence of the Picts and are thought to date from the 6th to 9th century, a period during which the Picts became Christianized. The earlier stones have no parallels from the rest of the British Isles, but the later forms are variations within a wider Insular tradition of monumental stones such as high crosses. About 350 objects classified as Pictish stones have survived, the earlier examples of which hold by far the greatest number of surviving examples of the mysterious Pictish symbols, which have long intrigued scholars.
In The Early Christian Monuments of Scotland (1903) J Romilly Allen and Joseph Anderson first classified Pictish stones into three groups. Critics have noted weaknesses in this system but it is widely known and still used in the field. In particular, the classification may be misleading for the many incomplete stones. Allen and Anderson regarded their classes as coming from distinct periods in sequence, but it is now clear that there was a considerable period when both Class I and II stones were being produced.
Later Scottish stones merge into wider medieval British and European traditions.
The purpose and meaning of the stones are only slightly understood, and the various theories proposed for the early Class I symbol stones, that are considered to mostly pre-date the spread of Christianity to the Picts, are essentially speculative. Many later Christian stones from Class II and Class III fall more easily into recognisable categories such as gravestones. The earlier symbol stones may have served as personal memorials or territorial markers, with symbols for individual names, clans, lineages or kindreds, although there are several other theories, and proposed explanations of the meanings of the symbols. A small number of Pictish stones have been found associated with burials, but most are not in their original locations. Some later stones may also have marked tribal or lineage territories. Some were re-used for other purposes, such as the two Congash Stones near Grantown-on-Spey, now placed as portal stones for an old graveyard. The shaft of an old cross is lying in the field. Another Pictish stone, the Dunachton Stone near Kincraig, was later used as a door lintel in a barn. This was discovered when the building was dismantled in 1870. The stone was re-erected in the field. Recently it fell, after being photographed in 2007, but was re-erected again a few years later by the owner of Dunachton Lodge.