We have an old house, it was built in the 1850s and is in great condition. One of the retaining walls has a large crack. It has been investigated and has been there since the 1940s and appears to be the result of bombings in the area in the 2nd world war. I now wonder what to do about it, the crack is about 2 inches wide. The house is fine but I dont know if it needs fixing, and how to approach that?