Short answers, pulled from the story.
Gamla Uppsala was the main religious, political, and legal centre of the Swedes from at least the 3rd and 4th centuries AD. The oldest Scandinavian sources refer to the ruler of the Swedes as the "King at Uppsala," and it hosted the Thing of all Swedes, a general assembly held every late February or early March.
Adam of Bremen described a nine-day festival held every nine years at which one human being was sacrificed each day alongside other animals, totalling seventy-two victims. Bodies were hung in a sacred grove adjacent to the temple; a Christian informant told Adam he had counted seventy-two bodies hanging there together.
The Royal Mounds, known in Swedish as Kungshogarna, are three large burial barrows dated to the 5th and 6th centuries. They are Sweden's oldest national symbols and are depicted on books about Swedish national identity. They were once associated with three kings of the semi-legendary House of Ynglings but are now identified by location as the Eastern, Middle, and Western Mounds.
Excavated by Bror Emil Hildebrand in 1874, the Western Mound contained the remains of a man buried with a Frankish sword adorned with gold and garnets, a board game with Roman ivory pawns, a garment of Frankish cloth woven with golden threads, and four cameos from the Middle East. The finds demonstrate wide-ranging contacts in the 6th century.
Gamla Uppsala became Sweden's first archbishopric in 1164. The seat was moved to Ostra Aros in 1273 at papal request; that town was then renamed Uppsala, which is why the original settlement is called Gamla Uppsala, meaning Old Uppsala.
Archbishop Valerius, King Eric IX of Sweden (before his remains were moved to Uppsala Cathedral), and the scientist Anders Celsius (1701-1744) are all buried at Gamla Uppsala Church. Anders Celsius was interred there alongside his grandfather Magnus Celsius (1621-1679).