what are the ways to preserve and protect monuments?

Answer 1

I'm wondering if you're talking about the ten commandments monuments or something else. National Monuments are managed by four U.S. Government agencies; the National Park Service, U.S. Bureau of Land Management and the U.S. Fish and Wildlife Service, under the U.S. Department of the Interior, and the U.S. Forest Service, under the U.S. Department of Agriculture.

There are also 'World Heritage Sites' protected by a part of the UN.

Other than that, I would assume state and local governments determine which sites to protect on their levels.

Could you be more specific?