The Adlerbogen (Eagle Arch) is a triumphal arch located on the eastern side of the Donnersberg. The steel structure was built in 1880, meant to honor Field Marshal Count Helmuth von Moltke and Chancellor Otto von Bismarck.

Shortly after the end of World War II, the Adlerbogen was destroyed—the eagle was shot off the top, the statue of Bismarck beheaded, and the statue of Moltke stolen. But in 2016, the arch was restored to its original design. The Adlerbogen is located on a forest path on the Donnersberg near Dannenfels and can only be reached on foot via various hiking trails. The car park at the Keltenhütte on the Donnersberg is already signposted on the federal and state roads in the area.