Arisen from an initially north-west German family of earls, the House of Oldenburg became a European dynasty in the 15th century. Genealogical chance as well as politically opportune constellations spread the reign of the House of Oldenburg and its various branches from their ancestral home to Schleswig-Holstein, the Scandinavian kingdoms, Russia and in the 19th century even to Greece. For the first time the complex history of the dynasty is laid out from the Middle Ages to the present day. This work takes the reader to the medieval county of Oldenburg, to Copenhagen, Stockholm, St. Petersburg, the metropolises of the early modern period along the Baltic sea and to Athens of the 19th century. Additionally it follows the rise of the line of the House of Glücksburg, which?s descendants are crowned monarchs in Copenhagen and Oslo today.