Over the years, the Eiffel Tower has been the site of numerous high-profile stunts, ceremonial events and even scientific experiments. In 1911, for instance, the German physicist Theodor Wulf used an electrometer to detect higher levels of radiation at its top than at its base, observing the effects of what are now called cosmic rays. The Eiffel Tower has also inspired more than 30 replicas and similar structures in various cities around the world.