"the chestnut trees in the beer garden opposite"

Modern day beer garden in Munich
Creative Commons Attribution Share AlikeModern day beer garden in Munich - Credit: Fritz Geller-Grimm
A beer garden is an open air drinking area attached to a pub or bar.  Before refrigeration, breweries would dig cellars to keep their beer cool, and plant chestnut trees on top of the cellars to provide shade.

Beer gardens are particularly common in Germany.