In 1903，still worried that his building might be torn down，Eiffel got a clever idea．He  asked the French military to conduct its own research on radio communications at the Tower．He even paid the army’s costs．

French army captain Gustave Ferrié worked from a little wooden house at the base of the  Tower's southern pillar．From there，he made radio contact with forts around Paris．Convinced of the importance of radio communications，the army set up a permanent radio station at the  Tower．In 1910，the city of Paris renewed the structure’s permit for another 70 years．  

This year marks the iconic structure’s 125th birthday．Over the years，research conducted  there has brought dramatic and unexpected payoffs．During World War I，for instance，the French army used the Tower as a giant ear to receive radio messages．It even led to the arrest of one of the war's most famous spies．