![u-bahn u-bahn](https://www.tekportal.net/wp-content/uploads/2018/11/u-bahn.png)
German or Austrian subway system, 1938 (originally in reference to Berlin), from German U-bahn, short for Untergrund-bahn, literally “underground railway.”
German or Austrian subway system, 1938 (originally in reference to Berlin), from German U-bahn, short for Untergrund-bahn, literally “underground railway.”