Düsseldorf is well known for its Altbier, a hoppy beer which translates as old [style] beer, a reference to the pre-lager brewing method of using a warm top-fermenting yeast like British pale ales. Over time the Alt yeast adjusted to lower temperatures, and the Alt brewers would store or lager the beer after fermentation, leading to a cleaner, crisper beer. The name "altbier" first appeared in the 19th century to differentiate the beers of Düsseldorf from the new pale lager that was gaining a hold on Germany.
