The earliest settlement on the island is thought to have been in the 5th century, perhaps by Christian missionaries. By the 7th century it was a Pictish fortress, and in the 9th century the Picts were displaced by Norsemen. Another Pictish fort on the northwest of Mainland Orkney is Gurness, a well preserved broch.
The Pictish settlement is attested by a small well and an important collection of artefacts (now in Tankerness House Museum, Kirkwall and in the Museum of Scotland, Edinburgh). Notable among these are a group of moulds for fine metalworking, showing that brooches and other ornaments were being manufactured on the site in the eighth century. The enclosure round the Norse church overlies a Pictish graveyard, and an important Pictish carved stone was found in pieces in this enclosure during site clearance (also on display in Edinburgh: replica on site). The most interesting Pictish remain found is a stone slab showing three figures and some additional Pictish symbols. It is not known what the subject of this carving is, but it likely shows aristocratic Picts as they wished to be perceived. This early eighth century slab shows a striking procession of three Picts dressed in long robes and bearing spears, swords and square shields. Above the figures are parts of four Pictish symbols (the warrior motif was adapted as the logo of John Donald Publishers Ltd, Edinburgh). Two simple cross-incised slabs, likely grave-markers, were also found in the graveyard, and are probably Pictish or early medieval in date (displayed on site).
Ruins of village
The Old Norse name for the island was "Byrgisey" which means fort island, and gives the parish its name. Brough, indeed, means fort (for etymology, see broch). At its east end are extensive remains of an excavated Norse settlement and church. Archaeological investigation has shown that these overlay an earlier Pictish settlement. There is a small site museum. The finds of Viking Era are also very rich, forming one of the best collections of such material in the British Isles.
According to the Orkneyinga saga the main residence of Jarl Thorfinn the Mighty (1014-1065) was located in Birsay, possibly on the Brough. At this time the first Bishop of Orkney was appointed and his cathedral was probably on the site of the present day Saint Magnus Kirk, nearby on the Mainland.
Many of the remains of these settlements are visible. The most significant being the remains of a fine, though small Romanesquechurch. This dates back to about 1100 AD and was dedicated to Saint Peter. It has an interesting shape; probably with a square tower at one end, and a semi-circular apse at the other. There is some evidence of an earlier, possibly Pictish church on the same site. The church was a place of pilgrimage until the Middle Ages. The remains of adjoining buildings round three sides of an open court suggest that it may once have been a small monastery (though there is no documentation for such a foundation).