http://www.paris-travel-guide.info/eiffel-tower-lightning-strikes/
What would happen if you were on the Eiffel tower when it was struck by lightning?
Not a lot apart from a loud bang. In a structure such as the Eiffel Tower the electricity runs across the outer surface. It’s the same principal that protects the passengers in a car or a plane should that get hit by lightning (planes frequently do).
This was something that the scientist Micheal Faraday investgated and he discovered that in a enclosed metal structure or a metal structure with a mesh construction the electrical charges are redistributed in such a way that they cancel out the electrical charge from the lightning within the structure itself. The name given to such a structure is a Faraday Cage, there’s more about it on Wikipedia http://en.wikipedia.org/wiki/Faraday_cage
Lightning Strikes the Eiffel Tower