It was conceived by Louis XV as a grand neo-classical church honouring St. Geneviève, the patron saint of Paris. After the Revolution, the building was converted into a mausoleum for the great philosophers, military, artists, scientists, and heroes of the French Republic. Occupants of the crypt include Voltaire, Rousseau, Victor Hugo, Zola, the Curies, and Alexandre Dumas (reinterred here in 2002). The view from the dome (206 steps) is marvellous. Check tour departure times at the information desk. A fascinating reconstruction of Foucault's pendulum also hangs within the Panthéon.