Allen loves rock 'n' roll. An expert guitarist, he pays a band to travel with him so he can jam whenever he wants. He owns a number of valuable guitars, including some previously used by Woody Guthrie and Jimi Hendrix.
In May, Allen showed off his skills at a celebrity-packed party he threw on his 414-foot yacht, "Octopus."
Octopus is truly one-of-a-kind, decked out with two helicopter landing pads and its own submarine. Allen has sailed to Antarctica, Europe, and other exotic destinations. "During the day we explore, and at night we jam," he told "60 Minutes" in 2011.
Allen owns a second yacht called "Tatoosh," a 313-foot watercraft that can accommodate up to 20 guests and 30 crew members. It also has a swimming pool, cinema, basketball court, recording studio, and two helicopter pads.
Sports are another passion of Allen's — he's a part owner of the Seattle Sounders, and he bought the Portland Trail Blazers in 1988 and the Seattle Seahawks in 1997. After the Seahawks won the Super Bowl in 2014, Allen threw a massive party that featured live performances from Macklemore & Ryan Lewis, as well as a set by Allen himself.
He also has a collection of vintage war planes that's rumored to be worth millions of dollars. He houses the planes in a museum called the Flying Heritage Collection, based in a hangar in Everett, Washington.
One plane in his collection is the MiG-29 Fulcrum, which was created by the Soviet Union's Mikoyan Design Bureau to challenge American fighter pilots in the 1970s.
In September, Allen filed suit when a Panzer IV tank he won at auction was never delivered into his possession. Allen reportedly paid $2.5 million for the rare German tank.
Allen is also known for his impressive real estate portfolio. In addition to vacation homes in London, France, and New York, he makes his primary residence in a 10,000-square-foot waterfront home on Mercer Island, a ritzy enclave of Seattle. He owns a total of nine mansions on the island, including one that's just for his mother and another that houses a full-size basketball court, swimming pool, and fitness center.
He gave "60 Minutes" a peek at the pool area during a segment that aired in 2011.
In 1997, Allen bought a 12,952-square-foot Mediterranean-style home in Beverly Hills, California. Among its ridiculous amenities is a funicular that shuttles guests from the pool deck to a tennis court located on a lower part of the property.
He also owns a 10-acre property in Kailua-Kona, Hawaii. Known as the "Thurston Estate," the property has a private harbor and boat shed.
Allen stocks his many homes with amazing works of art. Among the Microsoft billionaire's collection are works by Monet, Rodin, Rothko, Damien Hirst, and Alexander Calder. In 2009, Forbes reported that his art collection was valued at a staggering $750 million.
Like his Microsoft cofounder Bill Gates, Allen purchased a Porsche 959 in the late '90s, but it was held up in customs for a time because it didn't yet meet EPA standards. Though Gates helped pass a law that eventually got him his car, Allen was frustrated and decided to ship his Porsche back to Europe, where he still drives it today. When in Seattle, Allen opts for a much more modest 1988 Mazda B-Series pickup truck.
When he heard his favorite Seattle movie theater was going to be demolished, he decided to buy it. He refurbished the Cinerama with state-of-the-art sound and projection systems, including the world's first 4K laser projector.
Allen created a museum dedicated to rock 'n' roll in 2000. He later dedicated a portion of the space to science fiction memorabilia, which includes pieces — original pages from "Dracula," Jack Nicholson's ax in "The Shining — donated from his own personal collection.
In 2012, he opened the Living Computer Museum in Seattle, which he stocked with old computers that guests can play with. The computer includes early Apple and Microsoft models, as well as a 1960s PDP-7 that's the size of an office cubicle.