A brilliantly diverse category, encompassing the monastic liqueurs like Chartreuse alongside Italian classics such as Amaretto and Sambuca, cult drinks like Jagermeister and old stagers like Kummel. Many herb liqueurs contain dozens of different ingredients, the exact constitution and combination of which is invariably a jealously-guarded secret.
A sought after bottling of Yellow Chartreuse liqueur, made at their Tarragona factory and released sometime between 1966 and 1973. The story has it that this was produced in 1960 and then rested in casks until at least 1966 before bottling, but as with many stories around Chartreuse of this era it's far from certain.