I have been hearing a lot about Seattle in the news lately, but I don't know much about the city.  Is Seattle the capital of Washington state?  
No I believe Olympia is Washington's capital. Seattle is however the largest city in the state of Washington. 
What is the population of Seattle?  I assume several million.
Estimated 713,700 residents. That also makes it the largest city in the Pacific Northwest region of North America.
That's amazing.  Is there anything significant either historically or practically about Seattle?
Seattle has been one of the fastest growing cities in the U.S. It must be great there, since everyone is flocking to it.