The definition of public art to me means everything and means nothing because for me, all art is public. Art has to be public by definition and in a way It has to be accessible to any audience not just a work in a museum or an art gallery.
Fashion is for women without style.
Rome used to have good public art in ancient times. There is nothing like West of Rome in Italy.
There is something more profound than just real estate because the decline of retail is social. People don't go in small stores - that is a change that is happening in the consumer culture.