White Castle has its own take on fast food hamburgers. For starters, the patties are square, with five holes in each patty. And they’re small, too –- two-and-a-half inch sliders. Just big enough to fit into the palm of your hand. And since they’re steamed on a bed of onions, everything is infused with this very specific onion-esque flavor.Today, White Castles can be hard to find, depending on where you live. But KCUR's Mackenzie Martin, a producer at A People's History of Kansas City, says that this we stop thinking of White Castle as a semi-obscure cultural punchline, because over a century ago, White Castle invented something that became so important and all-encompassing that, today, it touches pretty much every person in America. Sometimes several times a day. Something that, in other countries, has almost come to define American culture: it has a strong claim to being the first fast-food restaurant.The White Castle System of Eating Houses