Many Viennese do their best to ignore them, but neither dynamite nor wishful thinking can rid the Austrian capital of the six anti-aircraft towers built during World War II, which are scattered throughout the city center. Like other grandiose architectural schemes of the Third Reich, the virtually indestructible citadels were intended to last for centuries. (With steel walls up to 16 feet thick, their proportions rival the Arc de Triomphe's.) Since there's no doing away with them, the Austrian Museum of Applied Arts wants to adapt one of the towers as an exhibition space. American artists Jenny Holzer and James Turrell have both submitted proposals, on view through November 10 at the tower in the Arenbergpark, in Vienna's Third District. Holzer, famous for her epigrammatic use of LED text, envisions a laser searchlight atop the hulking structure, tracing her inspiration to Vladimir Tatlin's concept for the 1919 Monument to the Third International, his paean to the Russian Revolution. Turrell hopes to construct a circular "skyspace" on one of the tower's four platforms that would also serve as a bar. Permanent conversion of the tower into a museum depends on approval from the city of Vienna and the Austrian government as well as on financial support from private sponsors. In the meantime, Austria's Green Party is lobbying to transform another of these monoliths into a Holocaust museum. The latest rumor is that a third may become a hotel.