at/on/in the department/faculty/chair

[tyrp]

Hello all,
Which preposition shall I use with department (meaning a university department, like that of social studies), chair (another uni structure, smaller than a department AFAIK, like the Chair of Service and Tourism), and faculty (the largest of the above if I get it right).
Are we practising/working/studying AT or ON the chair/department/faculty of...? There's also the preposition IN that has been left behind. Which of them is correct and do I understand the meanings of the words clearly? Thank you in advance.

[Tdol]

Chair to me is a single position help by a person, so we just say she or he is the xxxx Chair.

With Department/Faculty, I'd use at or in.

[tyrp]

Thank you for your advice and help.