Page 270 - Beyond Decommissioning

Experience and lessons learned 251

6.6.8 Climbing walls

Climbing walls have been mentioned in passing as innovative ways of converting
cooling towers at former power stations (Kalkar, Didcot). There are many more cases.
The rock climbing gym Allez-Up is part of the redevelopment project for Montreal’s
Southwest district, Canada. Adjacent to the Lachine Canal, the site and silos of an old
sugar refinery have been turned into an indoor rock-climbing facility, one more tourist
attraction of the area (Arch Daily, 2014). Five more climbing walls resulting from
reuse projects in Germany are described in Climbing (2017). See another case in
Section 6.6.9.

6.6.9 Flak towers

In 1942, Hitler had decreed that Vienna, Berlin, and Hamburg, should be protected by
a series of anti-aircraft towers known as Flakt€ urme (The word Flak is an acronym for
FLiegerAbwehrKanone, meaning anti-aircraft gun.) In Vienna three pairs of towers
were constructed by the Germans during 1943 and 1944. Each pair consisted of a
large, heavily gunned attack tower (Gefechtsturm) and a smaller communication
tower (Leitturm). Built of almost indestructible steel-reinforced concrete 3- to 4-m
thick, the attack towers were built either as a square fortress tower 45-m high and
60-m square with corner turrets, or as a circular tower 55-m high and 45-m in diam-
eter. The heavy artillery was placed on the roof, with lighter armaments placed on
projecting balconies. The towers were also used as bunkers and bomb shelters.
While some Flak towers in Germany were successfully demolished, those in
Vienna resisted demolition. Soviet troops tried to blow up one attack tower but man-
aged only to produce a crack around the top and to dislodge part of the balcony. The
other towers were too close to surrounding buildings to allow demolition with explo-
sives. So Vienna was simply rebuilt around the towers, which have now for more than
70 years been reminders of Vienna’s darkest hour.
Reuse of the Flak towers began decades after the end of WWII. Because their thick
walls keep interior temperatures constant and the reinforced floors are able to support
great loads, the towers make ideal structures for aquaria and vivaria, which require
environmental controls and huge water tanks. In Vienna the communication tower
in Esterha ´zypark has been successfully converted into the fascinating House of the
Sea (Haus des Meeres, in German) and now houses many aquatic species; besides
an elaborate climbing-wall has been installed on one of the exterior walls of the
Esterha ´zypark tower. The history and reuse of Flak towers is described in detail in
Smith (2005).
A WWII Flak tower in Hamburg, Germany had remained vacant for over 60 years.
After the end of the war this 42-m-high concrete giant could not be blown up without
endangering the close-by housings, so the Allies could only dismantle parts of the inte-
rior. From then on, the ruined building stood in the middle of the residential district,
virtually unused and at risk of collapsing.
The structure was converted in 2014 into a renewable energy plant and amenity
center. It is circled by a balcony open to visitors, above which four cylindrical