More than 7000 tons of iron and an adequate shape make the Eiffel Tower a long distance antenna. This principle was used in 1898 by Eugène Ducretet, and since then other successful tries were performed.
After these transmissions, the Eiffel Tower started to send TV and radio signals as another conventional antenna.
Some sources cite that in one of the four legs, there's right now even an underground radio studio. The tower has also installed multiple antennas; it's a clear broadcast center!