Before photography (or other forms of copying works of art) became available, how did the wider "art world" learn about new styles and new great works of art? Did painters, architects and sculptors travel around in order to see these works in person, or were new movements and techniques very localized and slow to spread out of their region of origin?
First, it was possible and common for images of art to be spread through copies well before the invention of photography. Engravings depicting new and famous works of art were widely available in cities throughout Europe. They were sold in print shops and street stalls, meaning someone who never left Antwerp could have some idea of what art in Italy looked like. This was huge business in the early modern period and there were skilled artists who specialized in creating images of other’s work.
Second, artists did travel and influence each other. Many artists trained in Italy and brought Italian trends home with them. Many artists also lived and worked in multiple cities in multiple countries throughout their lives.
Knowledge moved more slowly, but not as slowly as people think.