How do I rotate buildings before placing them?

I've seen people do this on Youtube videos (I think) and I want to know what buttons I press to rotate a building before construction. I can't find the controls to do this listed anywhere, though. What button is it?

when placeing, dont let go when you click where you want to place it, hold the mouse button down and move the mouse, it will rotate on point, albeit a bit awkwardly. Once you get used to it, you will notice that buildings will also snap to the sides of others.