In this week’s Flightless Bird, David Farrier looks at America’s obsession with sandwiches. Why is Subway the United State’s biggest fast food chain, leaving Starbucks and McDonalds in its wake? To get answers, David heads to Philly to investigate one of America’s greatest inventions: The Philly Cheesesteak Sandwich. There he discovers two sandwich stores locked in a decades-long rivalry. What’s the beef between Geno’s and Pat’s? And what of the man who supplies both stores with their tasty sodas? David also meets the man behind the popular Instagram account @SandwichesOfHistory, Barry, who recreates sandwiches of yore. Why were ancient sandwiches so disgusting? Why would someone combine peanut butter with tomatoes in a sandwich?