Imported Cinema 4D Problem

So the other day i was importing a huge city i made in c4d(Cinema 4D) into unity. It imported okay and fine but here’s the problem. The city and the land is not solid! I fall through everything i even added a mesh collider to it! But still didn’t work out… so how do i do this?

You probably only have a Collider on the parent object. You should add one to ALL of the children.

You can select ALL the meshes in the hierarchy, and then add a Mesh Collider by going to Components → Physics → Mesh Collider.