Prepositions can be used to show where something is located. In general, we use:
AT for a POINT
IN for an ENCLOSED SPACE
ON for a SURFACE
[ultimatetables 51 /]
Look at these examples:
When will you arrive at the office?
Do you work in an office?
Do you live in Bath?
Jupiter is in the Solar System.
The author's name is on the cover of the book.
You are standing on my foot.
There was a "no smoking" sign on the door.
The guide is waiting for you at the meeting point.
I live on the 3rd floor at number 21 Oxford Street.
Everything is so expensive on this menu.
Notice the use of the prepositions of place at, in and on in these standard expressions: