You have to be the initiator. Ask him to grab a bite to eat with you on your lunchbreak or after work. See how it goes from there. Well, if you have noticed he wears a certain kind of clothing line, or heard he likes a particular subject, those are always good icebreakers, it shows you payed attention to detail. If you know when he takes lunch then see if you can get the same time off and make it a point to introduce yourself more formally. There is a caveot to this. Office romances that do not work out become uncomfortable for everyone. Take the time to consider your career. I know it must seem flattering to have someone like you but I would err on the side of caution and evaluate if it will be worth mixing business with pleasure. You would not want to become office gossip, would you?