The following sentence stands isolated:
First, my attempt at translation: "With the world heritage, there are buildings and nature which we must from now on leave to our children and grand children."
I've no idea how to meaningfully translate this とは. と "adds up" with は here, but I can't make much sense of と in this position.
I must add that I feel very unsure about the whole sentence. I just learned about the -ていく construction which expresses that one is entering times of change from now on. I made 残していかなければならない an attribute to 自然や建物 because I couldn't muster an interpretation which would have made more sense. But I couldn't find a way to translate 残していかなければならない without 自然や建物 and this makes me doubt my understanding of the -ていく pattern...^^