The District 75 Office has secret floors that the elevator does not go to and that nobody knows about, except for the privileged few (i.e, custodial staff). They are used for storage. Also access to cool rooftop spaces
I got my first visit to the 9th, 10th and 11th floors about fifteen years after I started working here. Here are photos of the 10th and 11th floors.
Occasional Observations of Traveling Technology Coach 