Isenburg-Büdingen-Birstein was the name of a state of the Holy Roman Empire, based around Büdingen and Birstein in modern Hesse, Germany. Isenburg-Büdingen-Birstein was created out of a partition of Isenburg-Büdingen after the death of Count Louis II for his son John III. He was soon embroiled in a succession war with his brothers, especially Philip who established the state of Isenburg-Rönneburg. John was succeeded by three of his sons in 1533: Reinhard, Philip, and Louis III. Reinhard made his residence in Offenbach am Main, beginning the construction of his palace there in 1556. Castle Isenburg was completed in 1586 and stood as one of the greatest examples of Renaissance architecture in Germany.