Bismarck Tower, Memorial tower in Mülheim an der Ruhr, Germany

Bismarck Tower in Mülheim an der Ruhr is a 27.5-meter-high observation tower on the Kahlenberg hill above the Ruhr. It is built of Ruhr sandstone, with door and window surrounds, corner quoins and cornice of Niedermendig basalt lava. An internal staircase leads to the viewing platform.

Mülheim first planned a Bismarck column, but donations fell short; the ophthalmologist Johann Hermann Leonhard and his wife Margarete Stinnes funded the tower through their Leonhard-Stinnes foundation. Their nephew Gerhard Küchen chose the Kahlenberg site and supervised construction, while city building officer Carl Linnemann designed it. Work began in 1908 and the tower opened on 1 April 1909, Bismarck's birthday.

The tower was built to honor Otto von Bismarck and belongs to a series of similar monuments erected across the German Empire in the early 1900s. Such structures shaped the public landscape of German cities and reflected the political beliefs of those who commissioned them.

The tower stands at Bismarckstraße 22 on the Kahlenberg, on the right bank of the Ruhr, reachable by tram line 104 from the city centre to the Wasserstraße or Spielplatz stops. It has been closed to the public since 2018 because of structural defects, so the observation platform cannot currently be climbed; a support association is raising funds for the restoration.

In the basement studio of the tower, sculptor and painter Jochen Leyendecker (1957–2024) worked until the building closed; changing exhibitions there, including works by Edith Polland-Dülfer, made the tower a cultural venue. The tower has been closed to the public since 2018 due to structural defects, and a support association is seeking funding for its restoration.