The front of Union Depot in St. Paul is pictured on a cloudy March 16, 2016. (Andy Rathbun / Pioneer Press)

The Union Depot is seen under construction in about 1919. (Courtesy of the Minnesota Historical Society)

The skylights of the Union Depot's waiting room are seen Feb. 14, 2015. (Pioneer Press: Andy Rathbun)

A couple says goodbye in St. Paul's Union Depot on Jan. 8, 1949. (Courtesy of the Minnesota Historical Society)

The skylights in the Union Depot's head house are seen here Feb. 14, 2015. The Union Depot was downtown St. Paul's largest construction project in the 20th century. (Pioneer Press: Andy Rathbun)



The concourse connecting the waiting room to the head house has what is called a Guastavino tiled ceiling that features herringbone-patterned arches. It's seen here Feb. 14, 2015. (Pioneer Press: Andy Rathbun)

Passengers wait to board a train at St. Paul's Union Depot Jan. 16, 1949. (Courtesy of the Minnesota Historical Society)

School children look at the streamlined locomotive of the Burlington Zephyr from a platform at St. Paul's Union Depot on Feb. 26, 1949. (Courtesy of the Minnesota Historical Society)

The previous Union Depot faced Sibley Street and was where the arrival concourse of the present depot now stands. This photograph was taken shortly before the building was destroyed by fire in 1914. (File photo)

The interior of Union Depot's head house, seen here Feb. 14, 2015, features Tennessee marble on the floors, columns and walls. (Pioneer Press: Andy Rathbun)



Passengers buy tickets at the Union Depot on May 28, 1949 -- Memorial Day weekend and a peak travel day. (Courtesy of the Minnesota Historical Society)

The "Forever Saint Paul" mural in the depot's concourse, seen here March 9, 2016, holds the record for the largest Lite-Brite picture, according to the Guinness Book of World Records. Created by artist Ta-coumba T. Aiken, the mural uses about 600,000 Lite-Brite pegs. (Pioneer Press: Andy Rathbun)

Columns in the waiting room have "Central Standard Time" markings, seen here March 9, 2016, that are original to the Union Depot's construction. The markings once surrounded clocks that were kept synchronized by the depot's station master. (Pioneer Press: Andy Rathbun)

Above the windows of the Union Depot's waiting room is a terra-cotta frieze -- seen here March 9, 2016 -- that depicts the evolution of transportation from the ox cart to the electric train engine. (Pioneer Press: Andy Rathbun)

The Union Depot's waiting room features an acre of decorative plaster that includes 793 rosettes, some of which are seen here March 9, 2016. During its restoration, special tools had to be made to match the plaster's original cuts. (Pioneer Press: Andy Rathbun)



The white oak track cabinets in the Union Depot's waiting room, seen here March 9, 2016, are original to construction of the building. The wood even has its original finish. (Pioneer Press: Andy Rathbun)

An original marking denoting what was one of the Union Depot's train tracks, can be seen outside an original staircase at Gate B. (Pioneer Press: Andy Rathbun)

A westbound train approaches a control tower just east of Union Depot in St. Paul on Dec. 4, 1950. (Courtesy of the Minnesota Historical Society)

The Union Depot's waiting room, which extends the length of a football field, is seen from the depot's Red Cap Room on March 9, 2016. (Pioneer Press: Andy Rathbun)

Puzzle tiles that date back to the Union Depot's construction are seen on an original staircase near Gate B on March 9, 2016. (Pioneer Press: Andy Rathbun)



President Barack Obama speaks at Union Depot in St. Paul's Lowertown on Wednesday, February 26, 2014. (Pioneer Press: Scott Takushi)

Like the low rumble of a train far down the track, the past reverberates through the cavernous brick, stone and marble of St. Paul’s Union Depot.

This year, the depot officially turns 90. It was 1926 when one of the grandest buildings in the Twin Cities was finished, beginning decades of service as the launching point for St. Paul travelers.

After a four-decade absence of passenger trains, an extensive renovation re-opened the depot in recent years as a stop for railcars, buses and light rail. But thanks to extensive preservation work, the old remains with the new.

Here’s a look at 26 things that make the depot the unique landmark it is today.

1. Construction of Union Depot took more than eight years (1917-1926) — a delay was caused by World War I — and cost $15 million. In today’s dollars, that’s about $278 million.

2. After trains stopped running in 1971, alternative uses suggested for the depot included a U.S. Post Office mail processing center, children’s museum, and a river garden complex with office space and retail.

3. The depot was downtown St. Paul’s largest construction project in the 20th century. It was done in stages, as traffic and trains continued to move through the area.

4. The two-year renovation project cost $243 million — funded by the federal government, Ramsey County and the state — and was completed in 2012. More than 635,000 work hours were spent on the project.

5. The current building is the third iteration of Union Depot. The first opened in 1881, but was damaged by fire three years later. It was rebuilt, but fire struck again in 1913 and the building was destroyed.

6. The depot’s architect, Charles Sumner Frost, also designed the Milwaukee Road Depot in Minneapolis, which was built in 1899 and now houses a hotel and restaurant. Frost’s most well-known design work is likely Navy Pier in Chicago, which opened in 1916.

7. During World War II, the skylights in the waiting room were blackened with tar to protect troops from potential air attacks as they were deployed through the station. The windows stayed blackened until the building’s renovation.

8. Columns in the waiting room have original “Central Standard Time” markings. They once surrounded clocks that were kept synchronized by the depot’s station master.

9. The underground driveway below the depot’s front steps was designed as a taxi route that would allow VIPs to avoid the main lobby.

10. The waiting room is 360 feet long — the same as a football field. In total, the building occupies 290,000 square feet.

11. Above the windows of the waiting room, a terra-cotta frieze depicts the evolution of transportation from the ox cart through the electric train engine.

12. American presidents who have passed through the depot over the years include Calvin Coolidge, Franklin Roosevelt, Harry Truman and Dwight Eisenhower. President Obama gave a speech from the depot in 2014.

13. More than 20,000 passengers and about 275 trains a day passed through the depot during its peak traffic in the late 1920s and for a few years during World War II. In 1927, the busiest year in the building’s history, more than 490,000 tickets were issued.

14. You can buy a drink where train passengers bought tickets generations ago; the bar at Christo’s Greek Restaurant in the head house was once the depot’s ticketing windows.

15. The process to match the original paint scheme involved uncovering 24 layers of paint and three layers of primer. The gold represents the agricultural bounty of the state and green represents its forests.

16. The head house was placed on the National Register of Historic Places in 1974 and the concourse, waiting room and train deck were added in 2014.

17. If you hear a buzz about the depot’s roof, here’s why: five honeybee hives have been given a home there in an effort to support their community.

18. In the mid 2000s, space in the head house was converted into residences, and today there are 39 privately owned condominiums there.

19. The last of the original staircases is found at Gate B. It was formerly near the concourse and served rail tracks 1 and 2. The exterior of the staircase has original markings denoting the two tracks, and the stairs have original puzzle tiles.

20. The depot of today has local, express and regional bus connections; walking and bike connections; and connections to light rail, passenger rail, taxi services and car sharing. There are also four charging stations for electric cars.

21. The concourse connecting the waiting room to the head house has what is known as a Guastavino tiled ceiling featuring herringbone-patterned arches.

22. The number of travelers passing through the depot is just a fraction of what it was in the building’s heyday as a transportation hub. In 2015, an average of 697 people a day used the depot to access train, light rail and most of the bus lines.

23. The waiting room features an acre of decorative plaster that includes 793 rosettes. During restoration, special tools had to be made to match the plaster’s original cuts.

24. James J. Hill helped make the depot a reality. The railroad tycoon brought together several railroads to build the original depot, but he died before construction began on the building standing today. The Empire Builder train is named for him.

25. The white oak track cabinets in the waiting room are original to 1926, and the wood even has its original finish.

26. The “Forever Saint Paul” mural in the concourse holds the record for the largest Lite-Brite picture, according to the Guinness Book of World Records. Created by artist Ta-coumba T. Aiken, the mural uses about 600,000 Lite-Brite pegs.

For more on the Union Depot’s history, see John W. Diers’ book “St. Paul Union Depot.”