As Seattle tunnel project progresses, a look back at 30-year Denny regrade that 'moved mountains'

SEATTLE -- With Bertha, the tunnel-boring machine, back online and moving again it's a reminder of how Seattle continues to grow and redefine itself.

A great example of this is one of the largest city development projects in history, the Denny Regrade Project. Crews removed several huge hills during a 30-year period to allow Seattle to grow.

Historian Feliks Banel shows us how it happened.