Just a little background on the AOII house at Ohio University that KSUViolet06 so kindly posted. It was originally built in the early 1990's (1992 ish) as the Phi Sigma Sigma House. I remember being told during rush about a "secret room" that is built in the house but is not on the blueprints. AOII took over the house at the beginning of the 1996-97 school year (the year after I graduated). it is built onto the side of a hill and is really 3 levels, although you can only see 2 in the picture that was posted.
Anyway, prior to that AOII was located in what is now the Sig Ep house (picture below)
This house is supposedly haunted, although nothing out of the ordinary happened the year I lived there.
As for all of the other OU houses- most of them go back fairly far and the sorority houses tend to hold around 50-60 people.
