According to the dictionary, a corner is “a point where two converging lines meet, forming an angle, either external or internal”.
Which preposition goes with corner: in, on or at? The answer is the three o them can precede this word. However, the three expressions have different meanings:
When corner means an interior angle formed by two meeting walls, we use the preposition in. A piano was in the corner of the room.
On the corner means “occupying the surface”. For example, the shop in the picture is on the corner of the street. You can also say that a person is standing on the corner because they are occupying a space.
At the corner means near or adjacent to a corner. For example, you can say “Let’s meet at the corner of my street”. But you can also say that the shop is at the corner of High Street and Station Road, that is, when you give the name of the two streets that intersect each other, at is used instead of on because you don’t refer to the surface but the point of intersection.
Here’s a tip that can help you remember this: in is used with the idea of being inside a volume; on when there is an idea of surface, and at when we just mean a point or being near something.
See more at http://inmadom-myenglishclass.blogspot.com.br/2014/05/in-on-or-at-corner.html