Union Station officially reopens Saturday in Denver, and University of Colorado Denver history professor Tom Noel says it's arguably the most important building in the city.

The iconic building is again a center of transportation, offering bus, train and light rail connections. A hotel and shops have been added inside the building.

Noel says Union Station's historic importance stems from the critical role railroads played in the development of Denver.

"It was the railroads that really put Denver on the map," Noel says.

Denver almost became a ghost town when the Transcontinental Railroad bypassed the city, choosing to go through Cheyenne, Wyoming, rather than scale the Rockies west of Denver.

"Half of Denver moved to Cheyenne," Noel says. "So it looks like Cheyenne is going to be the rail hub of the Rockies."

But civic leaders in Denver, including former territorial Gov. John Evans and Rocky Mountain News founder William N. Byers, weren't going down without a fight.

"They said if the railroads won't build to Denver then Denver will build to the railroads," Noel says.

They raised the money to build the Denver Pacific Railway which connected Denver to Cheyenne in 1870. That prompted other rail lines to be built from the Transcontinental Railroad to Denver as well.

"And Denver begins to boom as the rail hub," Noel says.

That led to Union Station becoming the heart of the city. The station was opened in 1881, consolidating several small depots into one station, making transferring from one rail line to another more convenient.

The layout of Denver revolves around the station. With 17th Street running to the station, the road became Denver's main street. That is still seen today by the warehouse buildings, office towers and hotels that line the road.

Noel says the reopening of Union Station shows the building is still a driver of development.

"It's a wonderful return to the core city," Noel says. "Where as many core cities are decaying and rotting like Philadelphia, St. Louis, and even Chicago losing population, here you have an incredibly vibrant return to the city where that's once again the great transit hub that it was."