Paul Allen and Bill Gates met in high school while attending The Lakeside School in Washington. They became fast friends who got their start programming and hacking, thanks to the access they had to a mainframe system owned by their school. The school infamously bought what it expected would be a year's worth of time on the mainframe, only to find Allen and Gates had used up that time in just three weeks.

Soon, Allen was finding ways to sneak into computer labs and logging in as an administrator. Allen even passed himself off as a graduate student at the University of Washington, so he could get in some extra programming time. Eventually, he was caught and banned from the lab. Allen and Gates pressed on however. Their big break came when they saw an article about the Altair 8000 in Popular Electronics Magazine. The computer was small and inexpensive and was ideal for home computing. The two men got in touch with the computer's manufacturer and offered to design a programming language for the Altair 8000. That language was called BASIC, and its development opened their eyes to the potential opportunity that existed in creating a programming language. Oh, and yes, they designed it for a computer they not only didn't own, but one they had never even seen before. Incredibly, it was a success and their language worked.

Paul Allen co-founded Microsoft with Bill Gates in 1975. It was Allen who eventually dubbed their venture "Micro-Soft". They trademarked the shortened version "Microsoft" on November 26, 1976.

Mark Wilson/Getty Images

Fast forward to today and Paul Allen's net worth has skyrocketed to $20 billion. He is the owner of both the NFL's Seattle Seahawks (and has a Super Bowl win) and the NBA's Portland Trail Blazers. He lost his battle with non-Hodgkin's lymphoma this week. Allen was a lifelong bachelor with no children. His surviving family are his sister Jody and her three adult children.

Allen was a major philanthropist—he donated $95 million in the last year alone. However, Allen also took the time and spent the money to enjoy the spoils of his wealth. He owned a number of homes, yachts, planes, and an art collection.

Allen's sister and her children lived near him in Seattle. He owned at least nine mansions on exclusive Mercer Island. His main residence was a 10,000 square foot home with an indoor pool. Allen also owned an entire island off the coast of Washington—dubbed Allen Island, he purchased it in 1992 with the plan to build his dream home there. However, the lack of infrastructure led him to sell the island in 2013 for $8 million.

Allen's real estate portfolio spans the globe. In 1997 he bought the Beverly Hills property called The Enchanted Hill for $20 million. He demolished the Wallace Neff designed Spanish Colonial home that had been built on 24 acres in the 1920s. Allen never redeveloped the land. He put it on the market in July for $150 million. He also owned a contemporary home on Malibu's Carbon Beach which he bought in 2010 for $25 million. He sold that home to former CBS chief Les Moonves in 2014 for $28 million, allegedly because he hated the sound of the ocean. He also owned a 12,952 square foot mansion in Beverly Hills. In Northern California, Allen bought a 22,000 square foot, 8 bedroom, 9.5 bathroom home in the wealthy enclave of Atherton in 2013.

In Hawaii, Allen owned a $7.5 million, 10 acre estate known as the Thurston Estate on Hawaii's Big Island. The home in Kailua-Kona has a 12,000 square foot main house, a beach house, a house for employees, and a private harbor.

Allen also had a number of properties in New York City. He purchased an 18-room, 11^thfloor apartment at 4 East 66^thStreet in 1996 for $13.5 million. In 2011, he spent $25 million for the penthouse in the same building. The two apartments combined gave Allen an enormous duplex penthouse with a terrace space on the roof.

Outside of the U.S., Allen owned a home in London's chic Holland Park. In France, he owned the historic Villa Maryland which was built in 1904 for a friend of King Edward VII. The estate is perched on the Cote d'Azur and played host to a number of celebrity filled parties. Brad Pitt and Angelina Jolie were frequent guests.

TED ALJIBE/AFP/Getty Images

Allen was also a super yacht enthusiast. He bought Tatoosh in 2001 for $160 million. The ship can sleep 20 guests in 10 cabins, with room for 35 staff houses in an additional 16 cabins. Allen spent $200 million to build Octopus in 2003. The 414-foot yacht has a pool, two helicopters, a basketball court, movie theater, recording studio, and room for 26 guests in 41 suites. Allen also owned a 250.8 foot research vessel called the RV Petral. The RV Petral was refitted last year and has already found the wrecks of the USS Indianapolis and USS Lexington.

Allen also had an art collection that had him listed in the Top 200 Collectors by ARTnews since 1999. Following his death, the magazine wrote that Allen built "a highly regarded collection that was notoriously guarded – for many years, he demanded that his employees keep quiet about his holdings. In recent years, he began loosening the secrecy surrounding his collection, which focused on Old Masters, Impressionists, and modern and contemporary art, and included work by artists such as Renoir, Manet, Gauguin, and Seurat, as well as Mark Rothko, Edward Hopper, Alexander Calder, Ed Ruscha, and David Hockney."

In March, Allen sold a Willem de Kooning painting for $30 million.

Allen also had a collection of vintage planes that he began collecting in the 1990s. This collection is believed to be worth billions. It contains fighters and bombers from the U.S., U.K., Germany, Russia, and Japan.

What will become of Allen's vast fortune, properties, art collection, and other assets is yet to be known. We can assume his sister and her kids will receive a significant inheritance. Allen has also been a member of The Giving Pledge since 2010. He gave away hundreds of million before he died. A number of charities and his relatives are waiting to see where the balance of Paul Allen's fortune will end up.