The neoclassical St. Paul Union Depot was designed by the famous architect, Charles Sumner Frost in 1913. Construction began in 1917. The station had 10 platforms and 21 passenger tracks. Eight of the tracks ended at Union Depot. The building was completed in 1923. A roundhouse for servicing locomotives was located southeast of the depot complex. A two-story yard office building served as an operations center for train directors. For the passengers, the business lobby, concourse, and waiting room offered all the modern comforts of a real, big-city passenger station. There was a ticket office and baggage check, a Western Union office, telephone room, barber shop, drug store, coffee shop, dining room, and a newsstand. Restrooms had bathing facilities for the dirty traveler. The ceiling in the Concourse is in the Guastavino vault style that incorporates several layers of tiles laid out in a herringbone pattern. Because there are few recurring joints, the ceiling holds up well under heavy vibrations. The second floor of the Concourse and lower levels of the Head House contain areas for mail handling. When it was completed, Union Depot was the third-largest mail-handling station in the United States. Tunnels under Kellogg Blvd to transport used baggage between the baggage check room and the tracks.
