also on the wall stands: The Cross is my Anchor but mirrored

Thats no surprise. MTN is based on her clime back up after that stint with Def Jam. The anchor repesents the school she went to. It always was there. Gaga's tatoo is a "nod" to that.

I don't know what ARTPOP has to do with it. But that was a good observation with the anchor.

That's an actual mural, a depiction of the lost city of Atlantis. Idk why her anchor has anything to do with ARTPOP...she got an ARTPOP tattoo as well. Seriously reaching here.