Yes, all in all Portland is a very clean city. No graffitti on the Bridges ('though it appears sometimes <em>under</em> them.
Lots and lots of bridges. Here's a pic of one of them, the Burnside bridge:
There are some more in my "Bridges Gallery". Click the pic to go there...(I thought you'd never ask)
I have a long range project going to take pictures of all the bridges from Oregon City to the Coast along the Willamette and Columbia and south along the coast.