Not "forms of address", e.g., 'My Lord', 'Your Most Excellent Scholarhood',
et cetera, but "My office is at ...".
(N.B. Comments, please, especially if you know of other forms!)
Most of us are used to addresses of the form "123 Any Street", with a
fairly common variation of "Jedestraße 123". However, there are other ways
of defining where your office - or house, or store, or whatever - is. If,
in your worldbuilding, you use one of those other ways, you have another
hook to hang some potential trouble for your PCs...
All of the systems below are used in the real world. I even tell you where
I found it to be used.
In Nicaragua, addresses aren't numbered. Streets don't even have to be
named. Instead, the address is given by reference from a well-known
landmark location: "Iglesia Nuestra Señora de la Noche, 3 cuadras al Sud, 1
cuadra 10 varas al Este" (In English: "Church of Our Lady of the Evening,
three blocks south, one block ten varas east" [one vara is about 83cm]).
Pretty much anything can be the starting landmark - churches, parks,
important municipal buildings, gas stations... even a mile (well,
kilometer) mark along a highway. Sometimes, a landmark building gets torn
down. The addresses relative to that landmark only change with the addition
of "Donde Fue" at the beginning, meaning "Where was", or where the landmark
used to be: "Donde fue Igl.
N.S.de la Noche, 3 c. Sud, 1 c. 10 v. Este”.