On April 23, 1516, Duke Wilhelm IV endorsed the Purity Law for German beer, stating that just four ingredients can be used in the brewing process: water, malt, hops and yeast. 503 years later, the world’s oldest food regulation remains in effect.

On this date each year, German breweries, beverage dealers and many others who earn their bread by beer celebrate the occasion with special offers, brewery tours, tastings and other fun and educational activities.

Perhaps not surprisingly, beautiful Bamberg goes all out for the day, with many of its breweries setting up stands on the centrally located Maxplatz, where visitors can sample and compare wheat, Pilsner, smoke, cellar and other versions of the city’s best-loved beverage.

Even if you’re not lucky enough to anywhere close to Bamberg or Bavaria on this day, you might manage to find some kind of beer-related celebration at one of your local favorite watering holes. And if not, who’s to say you can’t crack open a tasty brew and hold a party for one? After all, you’re celebrating history! Prost!