In a sense this documentary could be a companion viewing to the 2021 movie "Eiffel" which focuses more on the man than on one project. Yet both seem to be consistent regarding the actual Eiffel Tower project.
This presentation, NOVA on PBS, shows that designing and building that tower in Paris was the breakthrough that resulted in the modern construction approaches that allowed the building of larger and larger, higher and higher, skyscrapers. Use of wrought iron built lighter and stronger structures while keeping costs in line.
The tower itself did not originate with Eiffel, already well-regarded for his innovative designs of such things as bridges and aqueducts, and of course the Statue of Liberty which has a steel structure inside to hold up the copper plates that make the exterior. Members of his engineering team suggested it, at first a rather simple tower in the general shape of what finally was built. But Eiffel took their simple designs and converted the whole project into something magnificent.
This is a really good documentary. It makes good use of photos taken during construction plus some inventive computer animation. A few things that I found interesting, the original lease was for only 20 years then the tower would be taken down. The metal is held together by about 2 1/2 million rivets. It has changed color a number of times over its lifetime, on average it is painted every 7 years and requires about 66 tons of paint.