Billionaire David Koch was one of the richest, most influential men in America - and he had a massive New York real estate portfolio

• David Koch was one of the richest men in the world.
• He owned a handful of properties in New York including a $40.25 million townhouse he reportedly paid for in cash.
• On August 23, 2019, he died at age 79.
• Visit Business Insider's homepage for more stories.

David Koch was one of the richest men in the world.

The billionaire conservative activist and industrialist had a net worth of $50.5 billion, per Forbes.

Along with unloading his fortune into Republican causes and local community projects, Koch also made heads turn with his real-estate purchases.

Read more: David Koch is dead. He and his brother Charles are worth over $50 billion each after years of family feuds and massive lawsuits - here's how they spend their wealth

Just last year, Koch and his wife were revealed as the buyers of Joseph Chetrit's $40.25 million Upper East Side Mansion. The New York Post reported that, according to sources, they paid for it in cash.

Koch was a familiar face in the world of New York real estate. According to the real-estate news platform Bisnow, along with the 15,000-square-foot townhouse, Koch also laid out $17 million in 2004 for an 18-room duplex in a luxury apartment building on Park Avenue.

In 2017, Business Insider reported that Koch owned a seven-bedroom home on Meadow Lane in Southampton, which Forbes once dubbed "Billionaire Lane."

On August 23, 2019, reports confirmed that David Koch died at age 79. According to his brother, Charles Koch, he battled with prostate cancer for 27 years.