The town at the head of the Oslofjord that grew from a settlement of about the year 1000 into the seat of a bishop, the shrine of Saint Hallvard and, under Haakon V from about 1300, the capital of Norway — guarded by the castle of Akershus he built and burnt out of existence by the fire of 1624.
Oslo stands where the long Oslofjord ends, on a bay ringed by wooded ridges, at the point where routes down the eastern valleys of Norway meet the sea. Snorri Sturluson credits Harald Hardrada with founding the town about 1049, and that tradition held for nine centuries; excavation has since shown urban occupation on the site before the year 1000, which is why the city kept its millennium in the year 2000 rather than in 2049.
The name is Old Norse and is read either as the meadow below the ridge or as the meadow of the gods, from ás. The medieval town was small by European standards — a few thousand people at its height — but it held a cathedral, a royal manor, several churches and monasteries, and after 1300 the government of a kingdom.
A bishopric was established at Oslo about 1070, in the reign of Olaf III, as part of the settling of the Norwegian church into fixed sees alongside Nidaros and Bergen. Its cathedral was dedicated to Saint Hallvard, Hallvard Vebjørnsson, a young man of the district killed about 1043 while trying to shield a woman accused of theft; his body, thrown into the fjord with a millstone round his neck, was said to have floated, and he became the patron of the city. His shrine stood in the cathedral and the saint still appears on Oslo’s arms.
The church multiplied its houses around the town. The Cistercians founded Hovedøya Abbey on an island in the harbour in 1174, and Dominican and Franciscan convents followed in the thirteenth century. Sigurd the Crusader, the king who had led a Norwegian fleet to Jerusalem, died at Oslo in 1130, and his death opened a hundred years of civil war in Norway.
In 1287 the Norwegian magnate Alv Erlingsson raided Oslo and showed how little the town could defend itself. Haakon V, who became king in 1299, answered by beginning a stone castle on the rocky headland of Akersnes at the western side of the bay, probably from the 1290s, and by shifting the weight of royal government from Tønsberg and Bergen to Oslo. He was the first king to live in the town as a matter of course, and by about 1300 it was the capital.
Akershus proved its worth quickly. Duke Erik Magnusson of Sweden besieged it in 1308 and failed to take it, and no medieval siege ever did; it held out again against Swedish attacks in 1449 and 1450. Haakon V died at Tønsberg on 8 May 1319 but was buried with his queen Euphemia in St Mary’s Church in Oslo, the church of his own royal chapel, which shows where he thought the kingdom’s centre was.
The Black Death reached Norway in 1349 and struck the town hard, killing a large part of the population and ruining the rents on which church and crown lived. Recovery was slow, and the political ground shifted underneath the city at the same time. Olaf IV was born at Akershus in 1370, and when he and then his mother Margaret I brought Norway into union with Denmark from 1380, the court that mattered moved to Copenhagen.
Haakon VI died in Oslo in 1380, the last king of the old Norwegian line to rule alone, and after him Oslo became the seat of a governor rather than a king. The town went on as the administrative centre of a kingdom governed from elsewhere, its cathedral chapter and its castle intact but its court gone.
The medieval city burned repeatedly, as timber towns did, and the fire of 1624 finished it. Christian IV of Denmark and Norway decided not to rebuild on the old site: he laid out a new town of straight streets under the walls of Akershus, the quarter still called Kvadraturen, and named it Christiania after himself. The old ground east of the river was abandoned, and the city kept the name Christiania until 1925.
What remains of medieval Oslo is therefore archaeology. The ruins of St Hallvard’s cathedral, the royal manor and St Mary’s Church are laid out in the Medieval Park beside the Alna; Akershus survives, though Christian IV rebuilt it as a Renaissance residence with Italian bastions, so the castle a visitor sees is Haakon V’s plan inside a seventeenth-century skin.