Need to conserve monuments?

There is a need to conserve the historical sites because they are the pride of the country. These were made by great persons of our historical times. But these days the historical monuments are been deployed by the hasty human practices, in the means of writing on the walls, spitting on the walls, etc. We can even see the other means of depletion by that of the nature by the global warming because as known we see the change of the colour and shade of the monuments.