Zwack Unicum is a brand of digestif amaro made by the Zwack company in Budapest, Hungary and imported by Diageo. It is a secret blend of over 40 herbs and spices, some macerated in alcohol and some distilled, then aged in oak barrels for six months.
The history of Zwack dates back to 1790, when Dr. József Zwack invented the liqueur for Emperor Joseph II. In 1840, his son Jozsef built a distillery that lasted until it was destroyed during World War II, eventually producing two hundred different liqueurs. Jozsef's grandson Janos and great-grandson Peter fled Communism, settling in the Bronx. The remaining members of the Zwack family created a false recipe -- the original one was smuggled out of the country.
In 1988, Peter returned to Hungary and bought his family's rebuilt distillery from the Russian government. Production of the original recipe began in 1990, and soon after, Peter became Hungarian ambassador to the United States.
Now in the sixth generation of family ownership, the company produces their flagship liqueur, Unicum, and a liqueur called "Next" that is relabelled in the United States as "Zwack". Both Unicum and Zwack are 80 proof.