Black, in the expansion of pi (3rd floor): 1
The length of the Mississippian age, rounded to the nearest whole standard square tile, times four (1st floor) 4*4=16
(salmon+red)^green+gray+blue, in the character tables (3rd floor) (3+1)^2+0+-1=15
Size, in small tiles, of Uranus (2nd floor) 12
Precessional period of the Foucault pendulum, to the nearest hour, divided by three plus one (1st floor) 33/3+1=12
Position of the third discrepancy between the two DNA sequences (2nd floor) 15
1, 16, 15, 12, 12, 15 => APOLLO