After millions of dollars in planning and years of arguing, state and local officials broke ground Wednesday on the project to build a tunnel under Seattle that will replace the aging, fragile Alaskan Way Viaduct.

The ceremony was at the south end of downtown, where workers will dig a pit at what will become the mouth of the tunnel.

The Washington State Department of Transportation says the largest-diameter tunnel boring machine in history will start digging the tunnel next summer.

"The Viaduct will fall down if we don't take it down," said Gov. Chris Gregoire at the ceremony.

When it's finished, she said, "a world-class waterfront in the city of Seattle will be ours. You and I will have a day to celebrate and be proud."

See the WSDOT's website on the tunnel project.