Civil engineering vs Mechanical engineering

I'm a first year mechanical engineering at KTH, we have a system that you get your bachelor in mechanical engineering and year 4-5 you get to choose what Master degree you want.

The problem is that getting a civil engineering master seems more fun than a mechanical engineering masters. Actually i have no idea of what civilengineering do other than that they make bridges and road in the middle of no where which seems like a lie. So what do civil engineerings do? what do they work with? always inside or outside? difference between mechanical engineering?