The pyramid used as an entrance in the Louvre's courtyard has the exact same proportions as the Great Pyramid of Giza. The choice of this figure also serves as a reminder of the importance of the Egyptian antiquities collection inside the museum, as does the Obelisk in Place de la Concorde not far from there, the other side of the Jardin des Tuileries. At its base, the pyramid measures 116 feet wide and 70 feet high. 95 tons of steel and 105 tons of aluminum support the structure.
The main pyramid is accompanied by three smaller ones. They have been positioned to create light shafts for access to the museum’s collections.
Lastly, the inverted pyramid is the one visible from underground, when you use the Carrousel entrance to the Louvre. In the proper sense, it is an upside-down, suspended pyramid.
Commissioned by the President of France, François Mitterrand, in 1984, it was designed by Chinese-American architect I. M. Pei. The structure, which was constructed entirely with glass segments and metal poles, reaches a height of 21.6 metres.
The pyramid and the underground lobby beneath it were created because of a series of problems with the Louvre’s original main entrance, which could no longer handle the enormous number of visitors on an everyday basis. Visitors entering through the pyramid descend into the spacious lobby then ascend into the main Louvre buildings.
According to pariscityvision.com and en.wikipedia.org