From the Federal perspective (the National Register of Historic Places is part of the National Park Service), a property owner can do whatever they want with their property as long as there are no Federal monies attached to the property.
I think you probably mean the metaphor of piercing eyes, it means someone who has a really intense look in their eyes. Sometimes it could be that the colour of their eyes is quite different, like a really icy blue colour. piercing eyes are eyes that can see straight through a person. SUPP is right.
Piercings are a form of self expression. People have been getting piercings done since the beginning of civilization. Nose rings and earrings are mentioned in the Bible as gifts for women. For everyone with piercings, they might actually mean something different. But it is certainly a form of expression or art, one way or another.