The ecclesiastical capital of medieval Sweden — an archbishopric founded at Gamla Uppsala in 1164, moved five kilometres south to the present city in 1273, and the shrine of Saint Eric.
Almost everything confusing about medieval Uppsala follows from the fact that the name moved. The older centre, now called Gamla Uppsala — Old Uppsala — lies about five kilometres north of the modern city and was the religious and ceremonial heart of the Svear, with its great burial mounds, its assembly and, from 1164, its archbishop.
The present city was a separate settlement at the mouth of the Fyris river, called Östra Aros, eastern river mouth. In 1273 the archiepiscopal seat was transferred there, and the name Uppsala was transferred with it at papal request. Statements about "Uppsala" before 1273 therefore usually mean the old site, and statements after it usually mean the new one.
The old site was the most important cult centre in eastern Scandinavia. Adam of Bremen, writing in the 1070s, described a temple there hung with gold and a grove in which men and animals were sacrificed every ninth year. He was a hostile witness who never visited, writing to justify a missionary programme, and modern archaeologists are cautious: excavation beneath the church found remains of one or more large timber buildings, but whether they are a temple, a hall, or an earlier church is disputed.
What is not disputed is the scale of the place. Three great mounds of the sixth century, an enormous hall platform, and a processional row of posts running for nearly a kilometre mark it as a royal centre for centuries before Christianity. The Christian church built there was made the seat of Sweden's first archbishop in 1164, when the Swedish church was finally separated from the archdiocese of Lund.
Eric IX was killed on 18 May 1160, the feast of the Ascension, at Östra Aros — the site of the present city — having heard Mass. His enemies, led by the Danish prince Magnus Henriksson, came upon him outside the church; the account has him finishing the service, arming the few men at hand, going out to meet them, being pulled from his horse and killed.
He was buried at the church of Gamla Uppsala, and a cult grew quickly around him. The detail of the story should be treated carefully: the narrative comes from a legend written more than a century later, and the only near-contemporary confirmation is a papal letter acknowledging that he was killed by enemies. He was never formally canonised by Rome, but he became the patron saint of Sweden regardless, and his feast on 18 May was kept throughout the medieval province.
A fire in 1240 damaged the cathedral at the old site badly enough that its nave and transepts were removed, and the practical case for staying was weak: Östra Aros was the working town, with the river traffic, the market and the population.
In 1273 the archbishopric and the relics of Saint Eric were moved to Östra Aros, which took the name Uppsala. Work on a wholly new cathedral in brick, on the French Gothic model and the largest church in Scandinavia, had already begun; it was consecrated in 1435. The shrine of Saint Eric stands in it, and the reliquary was examined in modern times, its bones showing injuries to the neck consistent with the manner of death the legend describes.
As an archiepiscopal city Uppsala held the provincial councils of the Swedish church, and its archbishop was the senior churchman of the realm, involved in every royal election and dynastic quarrel of the later Middle Ages. The cathedral became a royal burial church, and the shrine drew pilgrims from across the province.
In 1477 Archbishop Jakob Ulvsson secured a papal bull founding a university at Uppsala, the first in Scandinavia, on the model of Bologna and Paris. It struggled and effectively lapsed during the Reformation before being refounded, but its establishment completed the transfer of every institution that mattered from the old site to the new.