Unfortunately, it's right there in the center. It has to be easy for newcomers to see, after all.

At the top of the stairs is another set of offices. These are much larger, definitely the offices of people with some sort of direct connection to the mayor. These overlook the central foyer via a half-wall balcony, so Nyx, Cassian, and Crowe are able to see the entire set of offices from the top of the stairs.

At the direct opposite side, immediately above the front doors, an office door sits barely ajar.