Because their environment and security are not easily controlled, sites and monuments are more vulnerable than movable cultural property. Climate, vandalism, neglect, natural disasters, and indifference all contribute to the degradation of a site. Often when an archaeological team completes its excavation, it leaves the site to the elements with no plan in place for the site's preservation and care. The Anasazi sites in New Mexico's Chaco Canyon, for example, were widely excavated in the early part of this century with little thought given to how the architectural ruins would be protected once exposed. As a consequence, the U.S. National Park Service today is confronted with miles of masonry walls needing maintenance - and a shortage of resources to do it.
Sites can also be victims of mismanagement.
If a plan does exist but the site is poorly maintained, the typical result is decreased visitor respect for the site's physical integrity. Far too many sites, including some of world class stature, suffer from neglect or abuse. When governments perceive sites primarily as a mechanism for producing tourist dollars, sites can be destroyed through uncontrolled access. As more and more countries become accessible to tourism, there are going to be bursting points where sites suddenly receive all these tourists while lacking the infrastructure to deal with them. Site management plans today can have a variety of objectives, such as site development, increasing visitor access, and enhancing a site's educational value.