It sounds ridiculous now, but consider that when it was first put up, the Eiffel Tower was meant to be a temporary structure for the World Fair in 1889, with the term giving Eiffel the rights to commercial exploitation of the tower for 20 years, after which it was meant to be taken down. The terms required the tower to be build to be easy to dismantle.<p>Even though it was decided not to take it down in 1909 when the rights reverted to the city, it was not a given it would remain up permanently.