What if I don't know that there is no wall in the south of the building before handing over the house?

I realized that there was no wall on the south side of the building to reflect the property of the house. According to the public information of relevant materials, the walls in the building division belong to the owner except the roads in the town, and the owner has the right to manage and use the walls in some residential areas of * * * *, and the walls in some residential areas of * * * have collapsed or are missing, so the property can be required to be repaired.