Completed in 1892, Marble House measures 140,000 square feet and has 50 rooms. The construction alone cost $11 million in 1892, or around $380 million today when adjusted for inflation.

The wealthiest families of the Gilded Age lived in enormous mansions outfitted with gold, marble, and priceless art. Take a look inside.

The walls were also decorated with green Italian and French marble and Belgian tapestries from the 18th century. In Staatsburgh's drawing room, the Millses displayed three ancient Greek urns ...