How do fix this wierd lighting?

I was noticing this wierd problem for a quite a long time when i imported the area model. How do i fix this?

Recalculate the faces and the normals of the Model. If using Blender, just enter Edit mode, select all faces, in the ToolBox select Shading/UVs, Recalculate. Since this is a Interior model select “Inside”.

For some reason, the normal map of a texture im using is causing this problem. I just activated create from grayscale