Cimitero Monumentale: Pictures of one particular family grave

I spent a few hours back at Cimitero Monumentale today and managed to see just about all of it.  I even saw a cat and some lizards!  Most importantly though, I saw this:

I'm not entirely sure if this is information on how to contact the aliens, or a note for when the aliens land.  Either way, Dan Brown should stop making things up and just write all of his books about Cimitero Monumentale.