The palatial properties of America's wealthiest citizens come with sprawling residences, lavish interiors and decadence like you've never seen before.

With owners ranging from a Gilded Age railroad baron to a former president, each one comes with its own tale behind the dream – or folly – that led to its creation.

Click or scroll on to take a tour of the biggest billionaire mansions across the United States, complete with infinity pools, golf courses, secret roof terraces and even a flock of swans...