What's A Mega-Mansion?

I saw the Orange County Register's real estate blog had a post title referencing a "mega-mansion" and had to click through.  I thought that word "mansion" alone signified a big home, and that "mega" was a redundancy.  I am not so sure after reading about the 12.5-acre estate that has a 17,000 square foot house, private lake, tennis courts, an actual wine cave, vineyard and horse stables.   The estate is near the end of construction but financial problems have resulted in stopped construction and bankruptcy filings.  It was once valued as high as $81 million but now is being shopped at a lowly $37 million.  The home was owned and built by a partnership.  It filed for bankruptcy, following the bankruptcy filing of the mega-mansion's project manager / real estate broker.  There are 299 creditors that filed claims against the partnership.  The slide show of the estate is worth viewing.