Maze under Budapest hid a secret WWII aircraft engine plant

A hidden WWII aircraft engine plant is believed to have operated inside the maze of cellars beneath Budapest, according to a description drawing on Wikipedia. The Kőbánya cellar system under Budapest’s 10th district is characterized as the largest cellar complex in the country, with an estimated tunnel network of 32 to 35 kilometers beneath 44 to 54 acres. Originating in the Middle Ages as an underground limestone quarry supplying stone for landmark Hungarian projects, the area later hosted wineries and breweries, with the Dreher brewery still using parts of the cellars. During World War II, the complex’s size enabled it to function as a covert aircraft engine assembly plant and civilian hideout. Workers reportedly produced more than 200 Messerschmitt Me 210 engines underground until production shifted to Germany as Soviet forces neared Budapest. Moisture, mold, and groundwater flooding affected the spaces. A 2004 incident involved a 62-year-old man who died after falling into a pit in a park built over filled-in tunnels.