::*Agreed. Same with the World Trade Center. All demolished buildings are former buildings, but all former buildings were not demolished, as they may have been destroyed by fire, earthquake, collapse, terrorist actions or some other process other than their deliberate demolishing. I think it's probably more meaningful to use former buildings as the general container. The majority of former buildings will probably have been demolished, but it might be useful to group buildings that no longer exist because they were destroyed in some unplanned manner / act of God based on the manner in which they were destroyed. In this case, the Chicago buildings were demolished and replaced by other structures.