"Heimskringla; Or, The Chronicle of the Kings of Norway" by Snorri Sturluson is a collection of sagas written around 1230. This epic work chronicles Swedish and Norwegian rulers from mythological origins through 1177, blending Norse legends with increasingly historical accounts. Beginning with the legendary Yngling dynasty traced to the god Freyr, it progresses through centuries of kings, featuring conquests across Europe and the Middle East. The extensive saga of Saint Olaf II forms its centerpiece, while Harald Hardrada's dramatic exploits culminate at the Battle of Stamford Bridge in 1066.
from Old Norse Wikipedia page about this book: en.wikipedia.org/wiki/Heimskringla