Traveling, favorite places to visit and walk around?

I don't have a lot of money, but looking to do walking tours of areas. What are some spots you like to just walk around? Have you noticed any unusal or historical things right in the open? I love looking for things like that. I'm based in CO, but love traveling to new states.

Portland, OR is a great place for things like that. I don't live there, but love it when I go there to visit my daughter.