1. This vertical playground that's literally perfect for crowded cities. Goric / Via goric.com Walholla playgrounds were invented by the engineering company Carve when a Dutch city asked them to design a play space for a school that would have climbing equipment, could accommodate 60 children at a time, and leave enough room for a large soccer field. That means there's a lot of fun packed into the four-foot wide playground, which was so popular that it's spread to densely-populated urban areas like Washington, DC and Boston.(Click on any photo to enlarge!) 2. This colorful, hand-knitted net that's basically the most fun hammock ever. Getty Images You read that right — this bad boy is handmade! Woods of Net in Hakone, Japan, designed by Toshiko MacAdam, lets kiddos crawl, swing, and jump around on this awesome jungle gym, which is suspended inside an airy wooden structure at Hakone Open-Air Museum. 3. This play space that subtly teaches kids math as they frolic about. dpr.dc.gov / Via dc.gov Harry Thomas Sr. playground in Washington, DC is all about the golden ratio — its design features many different spirals, which were inspired by the Fibonacci sequence. Learning can be fun, guys! 4. This brightly-colored wonderland that's accessible for children of all abilities. Flickr: sabreguy29, Via fairfaxcounty.gov, friendsofclemy.com Clemyjontri Park in Mclean, Virginia, was specifically designed to allow children who use wheelchairs, walkers or braces, or who have sensory or developmental disabilities to play alongside their peers. Among the standard slides and bars are Braille signs, ramps, lowered monkey bars for easy access, and a wheelchair-friendly swing. It also has a carousel, a racetrack, and a maze! 5. This delicious-looking park that might get picky eaters to enjoy having their fruit and eating it, too. stockholm4kids.com Fruit is fab at Stockholm's Fruit and Scent Park, which is hidden at the end of a secret path. Youngsters can slide down banana peels, spin around on strawberries, and swing on cherries to their hearts' content. Orange you glad you know about this one now? 6. This multi-level playground that's big enough for adults to have some fun on it. imgur.com St. Louis' City Museum is basically a giant playground, and it has some amazing stuff: Two ten-story slides, a jungle gym suspended between two airplanes, underground caves, ball pits, and more. While it’s open to children during regular museum hours, it’s adults-only on Friday and Saturday nights at 9 pm — and the museum opens a bar. Cheers! 7. This combination playground and climbing course that offers a stunning view of Paris. BASE / Via baselandscape.com, instagram.com Children are encouraged to use their imaginations at Belleville Park in Paris, which is topped by an abstract play house that looks like anything from a pirate ship to a magical fort, depending on how you look at it. Either way, it's built into a steep incline, which means it has multiple climbing walls that overlook none other than the Eiffel Tower. 8. This playground that gives children total control over their playtime. yelp.com Kids can be the masters of their domain at Imagination Playground in New York City — literally. The interactive playground has big, blue foam blocks that children can arrange into whatever shape they want, from slides to forts. It also has mats, wagons, fabric, and crates, in addition to sand and hoses for anyone who prefers beachier types of playtime. 9. This splash pad that turns into an LED water show at night. Tomasz Zakrzewski / Via rsplus.pl Water Playground in Tychy, Poland, has all of the excitement of a water playground — whimsical fountains in a variety of colors make it look practically Seussian — but its built-in LED lights mean that the fun can go on after dark. 10. This fun-filled playground that's powered by solar electricity. playgroundprofessionals.com The sun fuels all of the fun at Kellogg Park in New Orleans, which was built to give children a place to let loose after the destruction of Hurricane Katrina. Kids can play on swings, climb on poles, and jump around on recyclable, non-toxic equipment provided by local suppliers. 11. This innovative, abstract play space that responds to touch. Free Play / Via freeplay.us.com If unstructured play time is the key to developing children's imaginations, then this interactive playground at Hazza Bin Zayed Stadium in Al Ain, United Arab Emirates, will create some pretty imaginative kids. The creative studio Free Play designed the space, which has a moveable maze and rope swings that make music, things that will engage the senses and make everyone feel like the king or queen of the playground. 12. And this monster park made entirely from recycled tires. Flickr: 135865815@N04 Godzilla won't actually eat anyone at Nishi Rokugo Tire Park in Tokyo, but children have a lot of fun pretending that the two-story sculpture of him might. In addition to Godzilla, adults and kids alike can play on a tire swing, a tire robot, and even a tire slide, all of which are made from recycled tires from the Kawasaki manufacturing plant. Sounds like it can get pretty tiring, huh?