"Where is the professor?"
Translation:¿Dónde está el profesor?
When you are talking about the position of something, the verb "to be" is translated as "estar" (and its conjugations).
Because it is talking about the verb Estar and Está is the conjugation for "Profesor" in this case.
For those familiar (and those who are not) with the Spanish word "catedrático" to denote a high-ranking academic professor (the more traditional UK meaning?), I tried it in my answer and it was accepted.
en el sistema universitario español,
un catedráticouniversitario es un profesor e investigador que ha pasado una serie de requisitos para alcanzar ese puesto fundeu.es
When you are talking about the location of anything (Even buildings), you must use "Estar".
I think your mistake is that you wrote "profeSSor" with two letters S, and the correct way in spanish is "profesor" with only one S.