Really funny findings are old 19th century beer caps. Around this period beer was still one of the most 'healty' beverages. In the early centuries even children drank beer. The reason was the fact that beer was brewed and bottled. It had none to very little possible bacteria in it - while water was in many cases polluted since water filtering systems were not yet used. The beers from those periods were always in glass bottles with cork - the cork was held in place by an aluminium beer cap, same as champagne bottles nowadays.
The most famous was HBM - Heineken Bierbrouwerij Maatschappij (Heineken Brewery Firm) which had some very nice period advertising!
From left to right: Amstel, HBM (Heineken), Drie Hoefijzers (Three Horseshoes - local Breda brewery) and Dommelsch. The state of these beer caps is quite remarkable.