Pantheon

In 1744, King Louis XV vowed that if he recovered from a mysterious illness he would replace the ruined Abbey of Sainte-Geneviève with an edifice worthy of the patron saint of Paris.
The king regained his health, and the Marquis of Marigny was entrusted with the fulfillment of the vow. Marigny's protégé Jacques-Germain Soufflot (1713-1780) was charged with the plans, and the construction of the Panthéon began.
The foundations were laid in 1758, but due to financial difficulties, it was not completed until after Soufflot's death, in 1789. As it was completed at the start of the French Revolution, the new Revolutionary government ordered it to be changed from a church to a mausoleum for the interment of great Frenchmen. Twice since then it has reverted to being a church, only to once again become a temple to the great men of France.

In 1851 physicist Léon Foucault demonstrated the rotation of the Earth by his experiment conducted in the Panthéon, by constructing the 67-meter Foucault's pendulum beneath the central dome

Here's Kelsey and the kids on the steps of the Pantheon