A place where mandatory meetings are held.
A mandatory place in which to go.

(n. pl.) Human resources policy documents, non-disclosure agreements, sexual harassment prevention training, workplace safety manuals, corporate mission statements, and other information that employees are required to read on a regular basis, even though the information has little or no bearing on 1) the reality of the workplace, or 2) the actual job function the employees perform. Most mandatoria is at least two years out-of-date and were written by HR drones who were laid off a few years ago.