NEED HELP W/ OUTSIDE LOCATION IN TUCSON

I am in need of help. My soon to be and myself have been looking around in Tucson to have our wedding outside and preferrably at one of these mansion size homes or something of that nature. So far we`ve really liked one spot but we will have to cut down our guest list by quite a bit. Any one know of mansion owners in Tucson or locations or this sort that will accomodate approx 400 people. Suggestions will be greatly appreciated.
Thx from the Soon to be couple who got married and lived happily ever after. :)