On May 15, 1940, the future of fast food was born in San Bernardino, California, when the McDonald brothers opened their first restaurant. But the original McDonald’s bore very little resemblance to McDonald’s as it exists today.

The original Mcdonald’s was an outdoor, slow-cooked, open-pit barbecue restaurant. The barbecue was cooked with hickory chips brought in from Arkansas for a special, unique flavor. While there were a few stools set up at the outside counters, most customers ordered from their cars and ate there, with their food brought to them by carhops. While the restaurant had its fans, the barbecue wasn’t terribly popular.

The hamburgers the restaurant made as a side item were rather popular, though. And the harder the brothers tried to sell their barbecue, the more people bought their hamburgers. So eventually, the brothers bowed to popular pressure and shifted their focus to their hamburgers.

To gain an edge over the competition, the brothers decided to adopt Henry Ford’s assembly line factory model to the food industry. Their “Speedee Service System” had employees trained to each work on a single station and rapidly assemble burgers, all in the same way. This meant that customers didn’t have to wait: they could often get their food immediately after handing the cashier their money. And this “fast food” made the McDonald’s restaurant into a huge hit, even if the menu was rather simple and limited: hamburgers, cheeseburgers, potato chips, pie, coffee, milk, and three different kinds of soda (but only one size of cup). Once they replaced the chips with fries and added triple-thick milkshakes to the menu, the restaurant’s popularity went through the roof.

Eventually, of course, McDonald’s became a franchise and then one of the biggest fast-food franchises in the entire world. Today, the only connection it has with the original barbecue restaurant is the sporadically available McRib barbecue sandwich.