They're abandoned for modern prisons because maintenance on older ones become expensive and costly. Especially over 100 year old prisons like the Reformatory and you also have to consider that alot of older prisons have dark pasts which equates to the lot of them being haunted.

And yes, the Reformatory is a gorgeous building. I actually need to take pictures of it when I get the chance but i've never done it because I don't know if and when it'd be considered trespassing and stuff. I just checked their hours so it seems I won't be able to go visit without notice until April hits since it's all reservation and other events that are only allowed to visit the building.