What do you do with your money when you're one of the world's wealthiest individuals?

Mexican entrepreneur Carlos Slim Helú is a self-made man, the son of Catholic Lebanese immigrants to Mexico. Today, he is the chairman and CEO of telecom giants Telmex and América Móvil. He has amassed a net worth upwards of $80 billion and often runs neck and neck with Bill Gates as the wealthiest man in the world.  Slim confesses to prefer "the simple life,” and his lifestyle may seem less extravagant than other billionaires. Still, Slim has been a savvy investor and businessman making sure that his fortune continues to grow. (For more, see: How Carlos Slim Built His Fortune.)

A man like Carlos Slim doesn't just keep billions of dollar bills stacked in a vault someplace. Here is where this billionaire stashes some of his money.

Investments in corporations

Slim holds stakes in many Mexican companies through his conglomerate, Grupo Carso. (The name 'Carso' stands for Carlos Slim and Soumaya Domit de Slim, his late wife.) Carso has accumulated a global portfolio of investments in companies dealing in communications, real estate, construction, airlines, media, technology, retailing, restaurants, industrial production, and finance. Currently Grupo Carso has a market capitalization of over $12 Billion.

Slim serves as the chairman and CEO of telecommunications firms Telmex and America Movil (AMX), with a market capitalization of over $80 Billion. Slim also has investments in various South American firms in Brazil, Peru and Colombia, including a controlling interest in Banco Inbursa.

Real Estate

Carlos Slim lives in a “modest” 6-bedroom home in the Lomas de Capultepec district of Mexico City, close to where he grew up, that has been his residence for over 40 years.

In Mexico, he owns over 20 shopping centers, including ten in Mexico City, and operates stores in the country under U.S. brands including Saks Fifth Avenue, Sears and the Coffee Factory.

Slim also owns the Duke Semans mansion (also known as the Benjamin N. and Sarah Duke House) on Fifth Avenue in New York City, one of the largest private residences in all of Manhattan. Paying a reported $44 Million for the property in 2006, it boasts over 19,000 square feet including 14 bathrooms, 12 bedrooms covering 8 stories. The property is included in the national register of historic places.

Carlos Slim has been reported to have acquired 417 Fifth Avenue, an 11-story office tower for $140 Million and also a piece of the former New York Times building on West 43rd street. He also has approximately 8 acres of prime Beverly Hills real estate at the corner of Wilshire and Santa Monica Boulevards. (For more, see: The Everyday Lives Of Frugal Billionaires.)

Planes & Automobiles

Carlos Slim's every day car is a custom Mercedes 4x4, which he likes to drive by himself even through heavy Mexico City traffic, and a beefed up Chevy Suburban for more rugged occasions. He also owns a rare Bentley Continental Flying Spur, a powerful luxury sedan few mortals can easily afford.

Though he eschews a private jet, Slim does fly occasionally on commercial airplanes, and sometimes he rides in the Telmex helicopter. (For more, see: What The Rich And Powerful Have In Common.)

Collectibles

While it's certainly an achievement to own one-of-a-kind real estate and rare cars, it is another to own precious, irreplaceable collectibles.

Named after Slim’s late wife Soumaya Domit, the Museo Soumaya opened in 2011, and features over 60,000 works of art by renowned artists like Rodin (he has over 380 Rodin works), Leonardo da Vinci, Picasso, and Renoir, as well as by Mexican muralists Diego Rivera and David Alfaro Siqueiros. Carlos Slim spent around $34 million to build the museum which was designed by architect Fernando Romero. This is also where he keeps his collection of rare coins, historical documents and religious relics. The artwork and artifacts inside are worth almost a billion dollars. Distributed between six main exhibition rooms, it is one of the largest museums of its kind in Latin America. The Soumaya Museum individual pieces and collections. Much of the museum's holdings are from Slim's own collection.

At home, Slim sips out of rare hand-carved and blown wine glasses by Baccarrat, which were owned by Porfirio Díaz, president of Mexico from 1876 to 1911. (For more, see: 6 Spending Tips From Frugal Billionaires.)

Transfers to His Children

Recently, Carlos slim has been allocating chunks of his business empire to his three sons and three daughters. Rather than simply handing his children cash, he is carving up and giving control of his businesses to them to run. Because Slim is in his 70's, this sort of estate planning ensures that his companies and wealth will continue to grow even after his death.

Philanthropy

Though Carlos Slim has more money than nearly everyone else on earth, he also gives away more money than nearly an individual on earth.

Fundación Carlos Slim, Slim's namesake charitable organization, focuses on philanthropy throughout Mexico and Latin America. Carlos Slim has contributed $100 million t Through Slim's Fundación Telmex the billionaire contributed $100 million to former President Bill Clinton's effort to fight poverty in Latin America. Slim also donated a similar amount to The Latin America in Solidarity Action Foundation (ALAS), a non-profit formed by businessmen, artists and prominent citizens to improve the health and education of Latin American children. In 2007 Slim created The Institute of Health Carlos Slim (ICSS) to improve health outcomes in Latin America. Perhaps because he is a secret lepidopterist, Slim donated $50 million to the World Wildlife Fund for the restoration of six endangered animal species in Mexico, including the monarch butterfly.

In 2000, Slim and ex-broadcaster Jacobo Zabludowsky organized the Fundación del Centro Histórico de la Ciudad de México A.C. (Mexico City Historic Downtown Foundation). According to his personal website, the goal of this foundation is to revitalize and rescue Mexico City's historic downtown area to enable more people to live, work and find entertainment there. (For more, see: 5 Billionaires With Multimillion-Dollar Pet Projects.)

The Bottom Line

For Carlos Slim Helú, savvy investing in a diversified portfolio of financial assets, real estate and collectibles helps to ensure that his wealth will continue to grow. But beyond that, his philanthropic mission to donate much of his wealth to that help better his home country of Mexico and Latin America may be his biggest investment and certainly a lasting legacy.