I have a Cat Cave but is more like a spare bedroom that I keep my clothes, books, and other junk in. Sometimes i'll lock my cats in there while we vacuum/clean the house.
It contains various KSU media guides, junk they hand out at games, newspapers after historic wins, and game programs from every basketball game i've been to. Also keep all the ticket stubs in a gallon ziploc freezer bag.
I also have a baseball signed by Pete Rose I keep in there, with a couple hockey puck (Espisito's, Bobby Hull)