Becherovka is an herbal bitters that is produced in Karlovy Vary, Czech Republic, by the Jan Becher company.

Becherovka is flavored with anise seed, cinnamon, and approximately 32 other herbs. Its alcohol content is 38% ABV (76 proof). It is usually served cold, and is often used as a digestive aid. Some serve it with tonic water, making a drink called a beton.

Today, only two people know the secret of the entire production process and may enter the Drogikamr room where, once a week, they mix the herbs and spices used in the drink. Some of the herbs are imported from abroad, and some grow around Karlovy Vary.

Source: Wikipedia