Eiffel Tower In 1909, a permanent underground radio centre was built near the south pillar, which still exists today. On 20 November 1913, the Paris Observatory, using the Eiffel Tower as an aerial, exchanged wireless signals with the United States Naval Observatory, which used an aerial in Arlington, Virginia. The object of the transmissions was to measure the difference in longitude between Paris and Washington, D.C. Today, radio and digital television signals are transmitted from the Eiffel Tower. A television antenna was first installed on the tower in 1957, increasing its height by 18.7 m (61.4 ft). Work carried out in 2000
Gustave Eiffel designed by Charles Garnier, later among the most prominent critics of the Tower. The dome, with a diameter of , was the largest in the world when built and used an ingenious bearing device: rather than running on wheels or rollers, it was supported by a ring-shaped hollow girder floating in a circular trough containing a solution of magnesium chloride in water. This had been patented by Eiffel in 1881. The design of the Eiffel Tower was originated by Maurice Koechlin and Emile Nouguier, who had discussed ideas for a centrepiece for the 1889 Exposition Universelle. In May 1884 Koechlin,