There are eight oversized, bright yellow canary sculptures made of hard plastic located on the grounds of the UNESCO World Heritage Site Zeche Zollverein in Essen. These sculptures serve both as functional waypoints and as an artistic tribute to mining history:

In early mining, canaries were used as an underground early warning system. Because they are extremely sensitive to odorless, toxic gases like carbon monoxide. If the bird stopped singing or fell off its perch, the miners knew they had to evacuate immediately.

• Because the figures stand unprotected outdoors, they occasionally suffer from severe storm damage or vandalism. Whenever a bird is damaged, it is temporarily removed, repaired and repainted and then reinstalled on its foundation. As a result, you might occasionally notice one of the eight birds missing for a brief "check-up" while walking down Bullmannaue. However, the complete installation of the "Designallee Zollverein" remains a permanent and defining feature of the World Heritage Site.