To celebrate Bastille Day (14 July) or the 1944 Liberation (25August), blue, white, and red laser beams are bounced off the Eiffel Tower, Arc de Triomphe, and Hotel de Ville.
No celebrations of any sort take place on Bastille Day. 
mnli hypothesis: No celebrations of any sort take place on Bastille Day.  premise: To celebrate Bastille Day (14 July) or the 1944 Liberation (25August), blue, white, and red laser beams are bounced off the Eiffel Tower, Arc de Triomphe, and Hotel de Ville.