It's both IN/AT University and AT home. The differences can sometimes be a little complex but here are some basic rules 1. IN to note a general location and AT for a more specific location. I'm in the building (general), at the front desk (more specific) I'm in New York (general), at the conference (specific) I'm in New York (general), at the Empire State Building (specific) 2. Note the difference when in is used to indicate INSIDE "I'm in the elevator" = I'm inside the elevator "I'm at the elevator" = I'm near the elevator Hope this helps even a bit

Use "in" when you're surrounded by a border of sorts... so you're in a room or building (walls), or in a city (city limits) or in a country (country borders), and so on. The simplest way to imagine "at" is that it's a point which you meet, in time or space. If you "go to" a place, then you "are at" that place, as a result.