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 Sotheby's employee holds a 110.03 carat sun-drop diamond on October 24, 2011 in London, England. The diamond is the largest yellow pear-shaped diamond in the world, and is expected to fetch between $11-15 Million USD when it is sold at auction at Sotheby's Auction house in London. (Photo by Dan Kitwood/Getty Images)

In this handout image provided by Sydney Tower Eye, a visitor scans the skyline and harbour of Sydney from a viewing platform at the Sydney Tower Eye, on December 16, 2011 in Sydney, Australia. Sydney is suffering from its coldest start to summer since 1960. (Photo by Eugene Tan/Hausmann Communications via Getty Images)

Archie McQuater, 82-year-old clockmaker at Craiglea clocks, adjusts a clock face to British Summer Time (BST) on March 25, 2011 in Edinburgh, Scotland. Clocks will be put forward by one hour at 1:00 AM GMT on Sunday March 27, 2011 officially the start of British Summer Time. British Summer Time will end this year on October 30. (Photo by Jeff J Mitchell/Getty Images)

A model showcases designs by Antonia Paris during the Women's RTW 3 catwalk during Rosemount Australian Fashion Week Spring/Summer 2011/12 at Overseas Passenger Terminal on May 5, 2011 in Sydney, Australia. (Photo by Stefan Gosatti/Getty Images)

A model showcases designs by Isola by Megan Gale on the catwalk at the David Jones Spring/Summer 2011 season launch at the Royal Hall of Industries, Moore Park on August 3, 2011 in Sydney, Australia. (Photo by Lisa Maree Williams/Getty Images)