The Venetian Macao, the world's biggest casino by gaming tables, photographed at its opening in 2007. - 

Macau didn't used to be on the radar of many foreign business owners, but it has swiftly become a global gambling powerhouse, attracting the likes of Vegas casino superstars Steve Wynn and Sheldon Adelson.

Gaming revenues from Macau are six times larger than what Las Vegas puts out. And revenues from Macau -- a 27 sq. km. territory -- are larger than all the casinos in the United States combined.

"The Venetian in Macau is, in fact, the biggest casino in the world and the 6th biggest building in the world, I mean it's truly enormous," says the BBC's Justin Rowlatt.

Rowlatt also told Marketplace host Kai Ryssdal that billionaire Sheldon Adelson makes more money in Macau than all his properties in Vegas.