1.   The damage done to manmade structures and to human beings by weather would be gone.

2.   In the resulting flooding, streams leap out of their channels into the roads and deposit gravel in their beds or eat away at the manmade structures.

3.   What were these retiring denizens of the rain forest doing near manmade structures?

4.   It appears to have foundations below the surface, and has the appearance of a manmade structure of huge blocks.