We've just moved into the home my grandfather built (1932). It was empty a couple of years after the passing of my mother who lived here last. After ridding the space of old furniture and freezers, tons of junk, etc. we can't seem to get rid of the constant "cat box" type odor that seems to be part of the cement floor and cinderblock walls. Even after a good scrubbing, eventually the smell returns. The basement is dry, and doesn't look moldy. The smell seems most prominant under the stairs. Most of the space is exposed building lumber, which is old chestnut.