Weird shadows on Static Meshes

I’m stumped on what is causing these shadows (not even sure if they’re shadows) on the corners of this building.

The weirdest thing might be that if I look at it from a certain angle, a small area of the shadow appears to disappear.

Any help is appreciated,
Mark

It does go away if i merge all the walls together but i’m still not sure what is causing this.

It also goes away if I don’t cast shadows from the skylight.