Build The Eiffel Tower is a French decision, building the world famous Eiffel Tower in Paris. It requires that the event Shall we host a world fair has happened to France, and that France has accepted to host the world fair. When that has happened, all France needs to do is the have researched Cheap Steel. The world fair can happen at any time between 1849 and 1935 to a great power with more than 200 industrial score or any civilized nation with more than 500 industrial score. It does however have a very long mean time to happen of 66 years. The mean time to happen does however get roughly halved as the game goes on.
It is important to note, that if the event for actually opening the world fair The World Fair is Opened happens, France will lose the modifier, which makes them able to build the tower. Therefore, it is very important to research Cheap Steel as soon as possible before the second event fires.
The decisions gives 22 prestige and on top of that, it gives 0.05 prestige pr. month for the rest of game (adding up to 1.2 prestige pr. 20 years).