When I was taking a quick stroll through the forums earlier today, I noticed that Swords had posted something about a huge tank in the chatbox. I grabbed the url and took a look. Wowza!
Apparently this guy built an addition onto his house where the addition is primarily a great room but one wall of it is a giant acrylic tank (& behind the tank is a utility room to house all the stuff for the tank). He had this as a reef tank for many years (won awards, etc) and has now switched it over into a massive paludarium.
Here's the link. I recommend starting from the last page so you can get an idea of the thing & where he's at with the progress.