The two-year renovation project has been led by architect Moatti-Rivieres, which also worked on new shops, restaurants and a museum to the first-floor area.
The glass floor has been added to the first floor of the 312-metre high building, allowing viewers to look down at the world beneath them from 57m above the ground.
A new cinema room screens films about the tower; while solar panels have been introduced alongside a rainwater collection system that will be used to supply water for the toilets.
Moatti-Rivieres worked with engineer Grontmij on the project, which aimed to make the first floor a feature in its own right.
The project also included the construction of three new glass pavilions at the site.