The Big Mac was invented in 1967 by Jim Delligatti, a McDonald's franchise owner in Pittsburgh, and has since been adopted by more than 100 countries worldwide to become a staple of pop culture.
The Big Mac now has a museum dedicated to it in the US, and continues to generate tens of millions of dollars every year for McDonald's, despite undergoing a sustained campaign of criticism by health lobbyists in recent years.
According to McDonald's latest estimates, around 550m Big Macs are sold in its US restaurants every year, equating to 17 every second.
The most high-profile attack to date, which came in Morgan Spurlock's 'Super Size Me', involved the documentary filmmaker eating only McDonald's food for 40 days to experience its effects on his physical and mental health.
The Big Mac was also lambasted in last year's film 'Fast Food Nation', a docudrama based on the book by Eric Schlosser, which criticised the fast food industry's impacts on the environment, workers' rights and health.
According to McDonald's own figures, a Big Mac bought in the US has around 540 calories and contains around 30 grams of saturated fat and one gram of sodium. However, figures vary greatly between nations, with a Big Mac in Mexico containing 600 calories per sandwich, while the same product would contain 464 calories in New Zealand and 493 in the UK.
In a further example of the Big Mac's global status, the sandwich has given rise to The Economist-devised Big Mac Index; an informal way of measuring the purchase power parity between currencies. Economists view the index as one of the world's most reliable financial indicators, given its ubiquity across all major global markets.
The Big Mac Museum, which was opened by Delligatti in North Huntingdon, Pittsburgh, yesterday to mark the sandwich's 40th birthday has been described by its founder as "an historical theme park" containing memorabilia and images from throughout its lifespan.