They didn't just make fortunes — they spent fortunes, too. It was a period of conspicuous spending that Mark Twain dubbed the "Gilded Age."

It wasn't called "the golden age" for a reason. "Gilded" meant the glitz and glamour were covering something not as shiny: rampant inequality.

The term was coined by Mark Twain and Charles Dudley Warner with their 1873 satirical novel, "The Gilded Age: A Tale of Today."

One of the defining features of the period was showing off.

The rich flaunted their wealth for everyone to see with the goal of one-upping each other.

There was a visible difference between old money families and the newly rich.

Across the country, especially in New York City, those with old money sought to keep their world to themselves, while the newly rich were busy building themselves extravagant mansions.

Not too far away on 73rd Street, steel tycoon Charles M. Schwab built himself a mansion made of steel, limestone, and granite.

The mansion had 75 rooms, a bowling alley, a swimming pool, and three elevators.

Perhaps most impressively, Schwab had an organ concealed by a tapestry that was woven by 100 Flemish women who had come to the US for that sole purpose, The Wall Street Journal reported.

It was demolished in 1948 and replaced with an apartment building.

Their library contained 8,000 volumes, including original books by Audubon and Shakespeare.

It also had a chandelier and a table with candelabras.

Building and buying mansions was only one way the newly wealthy would spend money in the Gilded Age. Shopping for clothes was another.

Every year, socialites would go to Europe to keep up with the latest fashions. The women shopped in Paris, while the men shopped in London.

The newly rich displayed their fortunes by attending the opera, access to which was controlled by old-money families.

In New York, a group with inherited wealth controlled who could get tickets to the Academy of Music, an opera house, and made it impossible for others to see a show.

In 1883, a group of newly rich families banded together to open the Metropolitan Opera so they could see opera performed, as well.

Gilded Age tycoons did some good with their fortunes, funding museums, orchestras, and opera groups.

Industrialist Andrew Carnegie, who donated money to fund more than 2,500 libraries around the world, said if a rich man died rich, he "died disgraced."

By the 1910s, the Gilded Age was coming to an end as the age of tycoons weakened and the underbelly of corruption was exposed.

Tycoons made their money at the expense of the working class. As newspapers exposed the underlying corruption that allowed an elite few to hoard enormous amounts of wealth, President Theodore Roosevelt imposed new limits on corporate power and established tax and political reforms.

It would take a few more years before the Gilded Age fully ended, but the days of ostentatious eating, spending, and partying were over.