Beneath the counter are many small holes labelled with the names of departmental staff members such as Donald Knuth, Per Brinch Hansen, Ken Thompson, and Niklaus Wirth. Either the labels or the holes themselves (the question is probably undecidable) change location from time to time. One of the holes is labelled "Peter Gutmann", although this is probably an allegorical representation rather than the real Peter Gutmann. If you ever need to drop off anything for him, this is where to do it.
Ring the bell and summon a secretary
Turn around and try the corridor instead