During the Gilded Age in the late 1800s, railroad tycoon Cornelius Vanderbilt was the richest man in America with a net worth of $100 million (around $200 billion today), more money than the US Treasury had at the time.
After Cornelius' death in 1937, his son William Vanderbilt took over the businesses and doubled his father's fortune. He died the wealthiest private individual in the world in 1885.
William's son Frederick Vanderbilt and his wife, Louise, purchased the 153-acre Hyde Park property in 1895. Construction on the mansion began in 1895 and was finished three years later. In total, the Vanderbilts spent $660,000 to build the home (more than $23 million in today's money) and $1.5 million (around $53 million today) to furnish it.