Construction of the imposing building started in 1757. Mainly due to financial problems, it would take 34 years until the project was completed. After Soufflot's death in 1780, his associate Guillaume Rondelet took charge of the project. The building was finished in 1791, in the midst of the French Revolution.
Assembly of the Revolution decided by decree to transform the church into a temple to accommodate the remains of the great men of France. The building was adapted by architect Quatremère de Quincy to its new function as a pantheon. In 1806 the building was turned into a church again, but since 1885 the Panthéon serves as a civic building.
The floorplan shows a Greek-cross layout, 110m long and 85m wide (361 x 279 ft). The large dome reaches a height of 83m (279ft). The portico, with large Corinthian columns was modeled after the 2nd century Pantheon in Rome. The dome features three superimposed shells, similar to the St. Paul's Cathedral in London. Iron reinforcements were added to strengthen the structure even more.
The large crypt, covering the whole surface of the building accommodates the vaults of great French public figures. Some of the most famous buried here are Victor Hugo, Voltaire, Jean Monnet, Marie and Pierre Curie and Emile Zola.