“Foucault’s original pendulum, which he used in 1855 to prove the world turns on its axis, is among the 80,000 instruments, machines and working models displayed at Europe’s oldest science and technology museum.” Check out the Metro station bearing the same name as the museum, it is made out of copper panels and is definitely one of Paris’ most beautiful.
Regular opening hours fee at 6.50€.
Free admission for all on Thursday from 6pm-9.30pm only.
Le Musée des Arts et Métiers 
60 rue Réaumur
Metro: Arts-et-Métiers, Réaumur-Sébastopol
Tues-Sun: 10am-6pm (until 9.30pm on Thursday)
Closed on Monday, May 1, Decembre 25