Modern graffiti have been inscribed upon the wall and tourist littering is a problem .
Fragments of the paintings have been removed as souvenirs and some surfaces have cracked after water was applied to ' enhance ' their contrast for photographs .
Modern graffiti have been inscribed upon the wall and tourist littering is a problem .
Fragments of the paintings have been removed as souvenirs and some surfaces have cracked after water was applied to ' enhance ' their contrast for photographs .