I was in Pompeii just 2 weeks ago, the thing that absolutely blew my mind was that there is a section where archeologists are working _right now_ still uncovering more buildings, and you can see them exactly as they are coming out of the ground - I think with the rest of the ruins I've had this feeling that you know, it got somehow cleaned up and repaired a bit for tourists, but nope, you can see in that section of active excavation works that these 2000 years old structures are really coming out of the dirt with the frescoes and mosaics still intact.
And then we went to Paestum, which is an even older Greek settlement in Italy - with the original Greek temples still standing. Mindblowing, and I'm used to old stuff being around(a friend of mine lives in a house where a portion of it is a listed structure dating to the 12th century, it's just a bathroom and a storage room for them lol).
The crazy thing is that Pompeii's art was so well preserved by the ash but now it is exposed to the elements and will degrade.
There's almost no original art in Pompeii, it's all in the archeological museum in Naples. There are some reproductions in place in Pompeii, but mostly it's bare brick walls that the art has been scraped from. You need to see the brick walls, then see the art in the museum, then compose the two in your head.
Yes, it will still degrade in the museum, is all I mean.