The Zollverein is a former coal mining compound in the Ruhrgebiet near the city of Essen. Construction began in the late 19th century and the compound was used throughout the 20th century. Today, the compound features museums and exhibits associated with the German coal mining industry, as well as a design museum and trendy restaurant. Kristin's sister lives in Essen and, as part of a visit last week, we explored this desolate compound.