Many of the places we saw were exhibits or even just old buildings constructed by earlier civilizations. Art is one of the best ways for one to express themselves in a way that says they were here.
While we can't always trace art to a name or a face, the art itself still holds the purpose of giving someone something to be remembered for, even if we don't remember the actual artist, the expression of the culture and life through these works is what creates a legacy for this person.
When we see ancient pieces of art or even ancient plays, we see a vision of what that person thought was valuable. Oftentimes, it allows us to see more about the world they lived in, or in the example of plays, the culture of the time. The legacy created is one where the exact name isn't important, but the world around the person is. We see the world through the eyes of a person living in it who was so inspired by this world that they created something that we can now remember them by.