Question

you visit a place of a hostorical importance with your friends and come accross people with their name and messages on the wall of the monuments

Answer 1

You should stop them and make them aware of the importance of those historical monuments
And if the don't understand then U complain to the authority
And if again there is no change then through social media you make people aware of the fact . Since we know that people are now a days very active so definitely any change will come