Politically speaking, it was a long and winding road to replace the viaduct. See the twists and turns that led to the new Seattle tunnel.

The grand opening of the new Seattle tunnel will be celebrated all weekend with more than 100,000 people expected to attend.

With anticipation building and festivities underway, it’s easy to forget the decades of drama that led up to the new tunnel under Seattle.

Before ground would ever break on the project, there were years of political battles, funding skirmishes, and competing ideas on how to replace the viaduct.

City and state leaders mulled options to keep traffic moving through the city: a new elevated structure, a suspension bridge across Elliott Bay, what about retrofitting the existing structure?

The most expensive option was a side-by-side, six-lane excavated tunnel covered with a lid. Then-Mayor Greg Nickels wouldn't have it.

"This region will not make the mistake of building another freeway on our waterfront."

In 2007, Seattle voters turned down both a tunnel and a new viaduct.

Enter two-term Washington Governor Christine Gregoire. The viaduct may have run through the city, but the "S-R" in SR-99 stands for State Route. And Gregoire would be the most consistent figure throughout the most debated years of the viaduct's future.

The eventual decision to replace the viaduct with a tunnel would come with a breakthrough in technology: the world's largest tunnel boring machine nicknamed Bertha.

Construction started in July 2013. The tunnel was supposed to open in 2016. But Bertha broke down and unexpected costs added nearly $58 million to SR 99 tunnel project price.

KING 5's Glenn Farley sat down with Gregoire and asked, "Did you ever think we'd get here?"