In the years between 1905 and 1910, in the picturesque landscape at the Lake Molchow near Alt Ruppin in the Mark Brandenburg, two spectacular country houses were built: Molchow House by the Finnish architects Herman Gesellius and Eliel Saarinen, and Kosmack House by the German architect and co-founder of the Deutscher Werkbund, Hermann Muthesius. The Molchow house was a rare example of a Gesamtkunstwerk, in which the planners were also responsible for the interior design down to the smallest details. It was also the only realized construction project of the famous North European architects in Germany. With the Kosmack House, Muthesius was able to realize his reform-oriented plan of a modern residential building, which was integrated into the landscape. This publication portrays for the first time in a comprehensive manner the two buildings, their inhabitants, their prominent guests as well as their eventful history until the demolition of the houses after the Second World War. It contains partly unpublished pictorial material on the two today defunct buildings and is based on the extensive research work of the author. (Das Buch wurde gefördert mit Mitteln aus der Glücksspielabgabe der Lotterien und Sportwetten des Landes Brandenburg.)