Every two years, Germany hosts the Bundesgartenschau, a federal horticultural show aimed at making cities greener. In 1959, the city of Dortmund was chosen to host the event, and to mark this occasion, a groundbreaking structure was conceived – The Dortmund Tower, or Florianturm. Designed by architect Will Schwarz, this iconic tower holds the distinction of being the first in the world to incorporate a revolving restaurant. Standing at 220 meters, it briefly claimed the title of Germany’s tallest building, offering visitors a panoramic view of the city and its lush surroundings.
Historical Context
The Dortmund Tower emerged during a post-war building boom across Europe, characterized by a spirit of competition among larger towns to erect monumental structures. This trend was noted in The Engineer’s January 1, 1960 edition, which highlighted the construction of the Dortmund Tower alongside other notable projects like the Stuttgart television tower and the Rotterdam Euromast. This era marked a shift toward the creation of tall, free-standing structures that defined the skylines of major cities.
Architectural Marvel
Constructed between May 22, 1958, and April 30, 1959, the Dortmund Tower is a reinforced concrete cylinder standing at an impressive 173.45 meters. The tower tapers from an outside diameter of 11.74 meters at ground level to 5.50 meters at a height of 133.2 meters. Its foundation, extending to -8.10 meters, consists of a circular concrete footing 25 meters in diameter, 2.5 meters thick at the center.
Structural Features
The Dortmund Tower boasts two sets of balconies – a lower, larger one between levels 133.2 meters and 144.7 meters and upper platforms from 151.8 meters to 155.5 meters. The lower balcony serves as a restaurant, accommodating 100 people, with a kitchen and offices situated at the lower level. The upper platforms offer an observation platform for 200 persons. Notably, the tower’s restaurant floor and glazed outer wall are a steel structure supported on rollers, allowing for a slow rotation by an electric drive.
Innovative Rotating Restaurant
The decision to include a revolving restaurant was a pioneering move, driven by several considerations. Besides providing a full panorama for every table, the rotating floor and windows aimed to maintain an even temperature inside the restaurant. The rotation addressed challenges of the glass deforming under thermal stress, ensuring a comfortable dining experience. An 8hp electric motor, coupled with a steplessly variable gear, facilitated speeds between 2rph and 6rph, allowing for a seamless rotation.
Telecommunications Hub
Beyond its recreational features, the Dortmund Tower served practical purposes. At the upper balcony, 151.7 meters above ground level, equipment for a directional telecommunications link was installed. Additionally, the tower supported horn and parabolic aerials, while two aerial masts for television broadcasting crowned the structure, reaching a combined height of 46.15 meters.
Evolution Over Time
Access to the tower’s observation deck was facilitated by high-speed elevators, ensuring a swift ascent in under a minute. Over the years, the Dortmund Tower underwent changes, including a reduction in height to 208 meters due to alterations in antennae configurations. Despite these modifications, the tower retained its significance as a symbol of architectural innovation and a testament to Germany’s post-war development.
Conclusion
The Dortmund Tower stands as a testament to Germany’s architectural prowess, marking an era of competition among cities to create monumental structures. Beyond its initial role as an attraction for the Bundesgartenschau, the tower’s rotating restaurant and telecommunications features added practical dimensions to its significance. As it evolved over time, the Dortmund Tower continued to capture the spirit of innovation and remains an integral part of Germany’s rich architectural legacy.
