Planning to build an archway between the hallway and living room. The problem is that the "opening" currently goes all the way to the ceiling, so I need to build a portion of the wall to mount the arch (arched). The existing walls are made of concrete and painted in both the living room and hallway, but it's probably better not to tamper with concrete, and it shouldn't be necessary since you can achieve the same wall color over the arch with a bit of paint.
I have never built a wall before, so I'm wondering if anyone can give me some tips on how to build this?