Usage of in and at: I'm in the university. vs I'm at the university.

[Sonubajwa2003]

I'm in the university

or I'm at the university.

Which one is grammatically correct?

Thanks.

[Morteza]

Hi,
Both of them could be correct.
We use "in" when we are thinking about the building itself,but "at" is used when we think of the place as a point or when we say where an event takes place.
It's always cold in Sue's house. (vs.) I was at Sue's house.
All the rooms in the hotel have TV. (vs.) We had dinner at the hotel.
Morteza

[Sonubajwa2003]

Thanks for clearning that up. I was always unsure about these two and thought I might be using them incorrectly. Will ask more questions as and when I face problem.

Cheers!