Short answers, pulled from the story.
Gamla Uppsala emerged as a dominant force in the Mälaren basin during the 3rd century AD. Early written sources describe it as the residence of Swedish kings from the legendary Yngling dynasty. The location held supreme authority over all other regions and became the largest settlement in Uppland during the Middle Ages.
Gamla Uppsala became Sweden's first archbishopric in 1164 marking a major religious shift. The stone building likely finished construction in the 12th century after an earlier wooden phase. The seat moved to Östra Aros which later renamed itself Uppsala following papal request in 1273.
Today only two hundred fifty barrows remain visible on the landscape out of the original two thousand to three thousand mounds. More than one thousand preserved archaeological remains exist within the parish boundaries. Most grave fields date to the Iron Age and the Viking Age instead of the Bronze Age.
Bror Emil Hildebrand directed work starting in 1846 into the nine-metre-tall Eastern mound hoping to find a king's grave. He dug into the western cairn in 1874 where he found charred funeral fire remains under cobblestones alongside a man and animals. Luxurious weapons included a Frankish sword adorned with gold and garnets confirming the power of the deceased.
The location lost strategic importance as land rose due to post-glacial rebound over centuries. Navigable waters gradually disappeared from the area reducing its accessibility. The seat moved to Östra Aros which later renamed itself Uppsala following papal request after 1273.