This book was written by Adam of Bremen in or around the year 1075. That, in and of itself, should be enough to make this very interesting reading if you are a history lover. This was written almost 1000 years ago; think about that, 1000 years ago!
The book is a compilation of 4 volumes written by Adam, a priest, as a treatise covering the history of the catholic church in northern Germany from 788 to his present time (approx. 1075).
It also addresses the mission of the church to preach to the northern islands (present day Scandinavia) as this was a part of the bishopric of Hamburg-Bremen and this is were the book is most interesting because it confirms the early Viking explorations to Iceland, Greenland and Vinland (most likely Newfoundland in Canada) which is to say that it is a record of the finding of North America before Columbus was even born; heck, this would be before Columbus' grandparents were born. Still bored?
Adam was a catholic priest of little renown in his time, but well educated, as his honorary title Magister Adam would suggest that he had passed through all levels of higher education. He was invited to join the church of Bremen by the archbishop and eventually became director of the cathedral's school. He composed this work whilst director of the school.
"Gesta Hammaburgensis ecclesiae pontificum" (Deeds of Bishops of the Hamburg Church) is Adam of Bremen's opus; a history of the actions of the archbishops of Hamburg-Bremen, originally written in latin as all 'gesta episcoporum' (deeds of bishops) were. It is a record of the accomplishments of the archbishopric (perhaps even written a bit boastfully) especially in the mission to save the savage barbarians of the northern islands.
This is a wonderful record of the dark ages including references to earlier works, which Adam would have had easy access to in the library of the church of Bremen, by historians such as The Venerable St. Bede ("the father of English History" & author of "The Ecclesiastical History of the English People"), Einhard (biographer for Charlemagne), and Cassiodorus (chief assistant to Theodoric the Great of Italy).
The first 3 books are a history and the 4th is more geographical. All information is, of course, relevant to the time it was written and needs to be confirmed, but the book on a whole is accurate for the time of the writing.
This is a wonderful source for anyone that is trying to gain an understanding of the dark ages, especially from the viewpoint of the catholic church which essentially ruled the dark ages.