Barry Levenson can tell you the exact date he became a mustard collector: October 28, 1986. It was the early morning after his beloved Boston Red Sox lost the World Series, and he was wandering an all-night grocery store "looking for the meaning of life," as his website puts it. Then, in a flash, it hit him: mustard. Barry would amass the world's largest collection, and people would journey from miles around to see it.

This unlikely epiphany set the course for the next 30 years of Barry's life. He began snatching up every type of mustard he could get his hands on, which wasn't always easy given his time-consuming job as the Assistant Attorney General for the State of Wisconsin. Once he even snagged a jar from a hotel hallway—and stored it in his pocket during a case in front of the U.S. Supreme Court. No one could accuse Barry of lacking commitment to his vision.

By 1992, he had compiled a large enough collection to open his dream museum. Today, the National Mustard Museum stands more than 5,624 mustards strong. The premier attraction—The Great Wall of Mustard—represents all 50 states and more than 70 countries. Elsewhere, visitors can play a Food Whiz game or gaze at a collection of antique mustard pots, tins, and advertisements. Of course, there are ample opportunities to taste the mustard, too. Visitors can typically sample around 500 varieties, and then pick a favorite one to buy and take home.