Gardar was the seat of the bishop in the Norse settlements in Greenland.

In the sagas, it is told that Sokki Porisson, a wealthy farmer of the Brattahlid area, launched the idea of a separate bishop for Greenland in the early 12th century. He got the approval of the Norwegian King. Most of the clergy would come from Norway. The first bishop of Gardar, Arnaldur, was ordained by the Archbishop of Lund in 1124. He arrived in Greenland in 1126. In the same year he started with the construction of the cathedral, devoted to St. Nicholas, patron saint of sailors.

The diocese was first assigned to the Archbishopric of Bremen. The diocese of Gardar was subject to the Archbishop of Lund from 1126-1152. In 1152 the diocese of Greenland, as well as those of Iceland, the Isle of Man, the Orkney Islands, the Faroer Islands became subject to the newly-established Archdiocese of Nidaros.

Bishop Arnaldur returned to Norway in 1150 and became bishop of Hamar in 1152. His successor was Jon Knutur, who served from 1153-1186. The third bishop was Jon Arnason, who took office in 1189. In 1202-1203 he went on a pilgrimage to Rome and met the pope. He died in Gardar in 1209 and was buried there, most likely in the Northern Chapel of the cathedral.

The next bishop, Por Helgi, arrived in Greenland in 1212 and was bishop until his death in 1230. In 1234 Nikulas was ordained, but he arrived in Greenland only in 1239. He died in 1242. Olafur was ordained in the same year, but arrived only in 1247. He remained bishop until the mid 1280s. He was abroad from 1264–1280, thus hardly serving in his own diocese. The next bishop was Por Bokki, who stayed in Gardar from 1289 until his return to Norway in 1309.

The next to serve was bishop Arni, who served from 1315-1347. Due to the poor communication between Greenland and Norway, it was assumed that he had died and a new bishop (Jon Skalli) was ordained in 1343. When it was discovered that the bishop was still alive, he resigned and never went to Greenland.

After the death of bishop Arni in 1347, it took a long time for the next bishop to arrive, mainly due to the worsening communications. Bishop Alfur was ordained in 1368 and served as last bishop of Gardar until 1378. The Greenland diocese disappeared in the 1400s, when the ship departures from Norway stopped.

Presently the settlement of Igaliku is situated on the same location. The site has been the subject of archaeological investigations since the 1830s. The cathedral has been the primary target of much of the archaeological work and was fully excavated in 1926 by Danish archaeologist Poul Norlund (1888-1951). Norlund made several scientific studies in Greenland starting in 1921 and ending in 1932.

Many ruins of the Norse settlements can still be seen in Igaliku today. The ruins mostly consist of the stone foundations of the walls in their original positions so that the extent of the settlement, both individual buildings and collectively, can be determined and understood. The main ruin is of the Gardar Cathedral, a cross-shaped church built of sandstone in the 12th century. The maximum length is 27 m, the width 16 m. There are also two large barns on the site with the capacity to have held up to 160 cows. The see ran the largest farm in Greenland.

Information based on,_Greenland