http://www.pacapitol.com/plan-a-visit/tours.cfm
Ditto.
Just go through the main entrance in the front of the building on 3rd street. Once you pass through security, you will find a visitor desk to the right. That is where the Capitol tour guides are. They can schedule one for you when you show up. The tours go every 30 minutes or so. I think they occure during regular business hours during the week and they have a shorter window on Saturday.
They give tours every 1/2 hour. Just show up during the day, and sign up for one.
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