eyebrow windows

i've always loved design. i used to spend sunny saturdays in college walking around town taking pictures of historic homes. yesterday on a city walk, i learned a new architectural term: eyebrow windows. i am excited to learn more so that when i see a row of distinctly different homes, i can name the style and building date. right now i only know i'm not wild about columns (unless essential to a porch and very well done) and somewhere in my archives i can recall the terms doric, gothic and corinthian. but i have miles to walk and books to read before i can speak with any intelligence on the subject. do you have a favorite architecture or design book to recommend?