I have read the admission fees for Musee D'Orsay and Louvre, and both state if under 18 get in free. I will travel with my two daughters ages 13 and 16 into these museums. I plan to get a pass or ticket for me, but if they are free does anyone know, do they just show their passports for proof of age? Or do I need to get a student pass or ID for them to show for entrance? My oldest daughter is not obviously less than 18.