I would say it is their style and more specifically the way they constructed their buildings with roman columns. The columns were very detailed and heavy. It was so important and fascinating to our modern day citizens that even the white house is built with roman like columns. I would say the columns is the architectural feature from rome that we use commonly in modern-day structures.
Different colors express different moods, for example we often associate red with anger, blue with sadness. So the color can affect the mood set for you artwork. Also, in like abstract drawings it can help you because we often associate colors with certain landscapes.
