Inauguration and the 1889 Exposition ( Eiffel Tower )

The main structural work was completed at the end of March 1889 and on the 31st Eiffel celebrated this by leading a group of government officials, accompanied by representatives of the press, to the top of the tower. Since the lifts were not yet in operation, the ascent was made by foot, and took over an hour, Eiffel frequently stopping to make explanations of various features. Most of the party chose to stop at the lower levels, but a few, including Nouguier, Compagnon, the President of the City Council and reporters from Le Figaro and Le Monde Illustré completed the climb. At 2.35 Eiffel hoisted a large tricolore, to the accompaniment of a 25-gun salute fired from
the lower level.[24] There was still work to be done, particularly on the lifts and the fitting out of the facilities for visitors, and the tower was not opened to the public until nine days after the opening of the Exposition on 6 May, and even then the lifts had not been completed.
The tower was an immediate success with the public, and lengthy queues formed to make the ascent. Tickets cost 2 francs for the first level, 3 for the second and 5 for the top, with half-price admission on Sundays, and by the end of the exhibition there had been nearly two million visitors.[25]
Eiffel had a permit for the tower to stand for 20 years; it was to be dismantled in 1909, when its ownership would revert to the City of Paris. The City had planned to tear it down (part of the original contest rules for designing a tower was that it could be easily demolished) but as the tower proved valuable for communication purposes, it was allowed to remain after the expiry of the permit. In the opening weeks of the First World War, powerful radio transmitters were fitted to the tower in order to jam German communications. This seriously hindered their advance on Paris, and contributed to the Allied victory at the First Battle of the Marne.[26]

( From Wikipedia )