The Arizona State Capitol Museum is located in Phoenix, Arizona—not Arlington, Washington.
1700 West Washington StreetThe museum occupies the historic 1901 Capitol building. Exhibits cover Arizona's territorial days, statehood (1912), government, and natural history. Free admission. The Capitol Museum Guild supports programs and gift shop.
Arlington, WA (Snohomish County) has no Arizona Capitol connection. Likely confusion with "Washington" as in D.C. or state name.