This person has already posted this question two other times, one of which I replied: http://talk.collegeconfidential.com/george-washington-university/1913459-george-washington-university-open-house-dates.html#latest
Long story short, there are no open houses. You can take a tour on a scheduled date/time like @MommaJ said. If you want to know about school specifics (even though it looks like “open houses” are only for grad students) call the school directly:
Elliot: 202-994-6240
Columbian: 202-994-6210