Last weekend, the National Building Museum in Washington, D.C., opened a 10,000 square-foot ball pit to the general public, and everyone cheered that, finally, someone made their childhood dreams come true.

A shoebill is displayed at Ueno Zoo in Tokyo August 28, 2012. (Photo by Itsuo Inouye/Associated Press)

A masked protester talks to a soldier during clashes after the funeral of Brig. Gen. Wissam al-Hassan October 21, 2012. Lebanese soldiers fired guns and tear gas to push back hundreds of protesters who broke through a police cordon and tried to storm the government headquarters in Beirut. (Photo by Hussein Malla/Associated Press)

The Lumix GX1 single lens reflex (SLR) camera with 14-42 mm powerzoom lens is displayed at the Panasonic booth at the 2012 International Consumer Electronics Show at the Las Vegas Convention Center January 10, 2012 in Las Vegas, Nevada. The new camera comes with an external viewfinder and flash and an ISO up to 12,800. The camera as shown sells for USD 949; the camera body alone is USD 799. (Photo by Ethan Miller/Getty Images)

Chinese military medics take part in a parade commemorating the 70th anniversary of Japan's surrender during World War II held in front of Tiananmen Gate in Beijing, Thursday, September 3, 2015. (Photo by Ng Han Guan/AP Photo)

“The last known individual of the subspecies was a male named Lonesome George (Spanish: El Solitario Jorge/George), who died on 24 June 2012. In his last years, he was known as the rarest creature in the world. George served as a potent symbol for conservation efforts in the Galápagos and internationally”. – Wikipedia. (Photo by Rodrigo Buendia/AFP)

In this handout photo provided by Warner Brothers Pictures and Village Roadshow Pictures, Tom Cruise plays Lieutenant Colonel Bill Cage, a soldier who replays his last day while trying to fight aliens, in director Doug Liman's “All You Need Is Kill”. The film is set to premiere on March 14, 2014. (Photo by David James/Warner Brothers Pictures)

June 21: “World War Z”. Brad Pitt battles zombie apocalypse in $170 million film by “Quantum of Solace” director Marc Forster. This publicity photo released by Paramount Pictures shows, center, Brad Pitt as Gerald Lane in a scene from the film, “World War Z”, from Paramount Pictures and Skydance Productions in association with Hemisphere Media Capital and GK Films. (Photo by Jaap Buitendijk/AP Photo/Paramount Pictures)