What do you mean by "structure"? Su oficina is the subject. Está is the verb. En el centro de la ciudad is the location complement. It's telling where the office is located.

“Su oficina” – subject "estás" – verb . it equal to "is" en el centro de la ciudad–adverbial.It means :in the centre of the city

Su = it is an article, it is telling that the noun is indefinite. Oficina = it is a noun, it is "office" in English. Está = it is a verb. It is the Spanish for 'is'. En el centro de la ciudad = it is a circunstancial complement, it is indication a place Su oficina = that is subject. Está en el centro de la ciudad = that is the predicate. I hope this helps you! If you have more questions, feel free to ask! :)

Your sentence is well done. If you want to define the pronoun you can do the following: La oficina de él está en el centro de la ciudad. (If you are talking about him) La oficina de ella está en el centro de la ciudad. (if you are talking about her) Su oficina está en el centro de la ciudad. (In this case the person can be natural [he, she] or artificial [a bank office and so on and so forth]). See you.

Qué quieres saber exactamente?