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 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 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.

Adam based his works in part on Einhard, Cassiodorus, and other earlier historians, consulting the library of the church of Bremen.

[1] After the death of Bishop Leuderich (838–45), the see was given to Ansgar, it lost its independence, and from that time on was permanently united with the Archdiocese of Hamburg.

Adam is also an important source of Viking Age Norse paganism, including the practice of human sacrifice:[2] The description of the temple at Uppsala is one of the most famous excerpts of the Gesta: The fourth book describes the geography of Scandinavia and the Baltic region.

Adam of Bremen had been at the court of Danish king Sven Estridson and was informed about the Viking discoveries in the North Atlantic there.

His position and the missionary activity of the church of Hamburg-Bremen allowed him to gather information on the history and the geography of Northern Germany.

A stay at the court of Svend Estridson gave him the opportunity to find information about the history and geography of Denmark and the other Scandinavian countries.

He had access to the biographies of the missionary saints Boniface, Ansgar, Liudger, Radbod, Rimbert, Willehad and Willibrord.

Among ecclesiastical texts, he used the False Decretals, the Decretum of Burchard of Worms and lost work by Abbot Bovo II of Corvey.