Adam, von Bremen, active 11th century. Gesta Hammaburgensis ecclesiae pontificum

Gesta Hammaburgensis ecclesiae pontificum (Medieval Latin for "Deeds of the Bishops of Hamburg") is a historical treatise written between 1073 and 1076 by Adam of Bremen, who made additions (scholia) to the text until his death (possibly 1081; before 1085). It is one of the most important sources of the medieval history of Northern Europe, and the oldest textual source reporting the discovery of coastal North America. It covers the entire period known as the Viking Age, from the foundation of the bishopric under Willehad in 788 until the rule of prince-bishop Adalbert in Adam's own time (1043–1072). The text focuses on the history of the Hamburg-Bremen diocese and its bishops. As the bishops had jurisdiction over the missions to Scandinavia, it also gives a report of the Norse paganism of the period. The existence of the work was forgotten in the later medieval period, until it was re-discovered in the late 16th century in the library of Sorø Abbey, Denmark.