The Marquam Bridge is a bridge in Portland, Oregon that carries Interstate 5 over the Willamette River. Starting from the north, it is the seventh of eight bridges that cross the Willamette in the area of downtown Portland. It was also the seventh to be built, in 1966, as part of the Eisenhower Interstate System.
The bridges across the Willamette are one of the most recognizable features in Portland, and all of them have important architectural and historic significance. The bridges are not just the type of thing that is used to decorate tourist brochures, either. they are something that Portlanders actually use daily for practical purposes, and also because they are fun to just walk across and visit.
And then there is the Marquam bridge. It has a separate use and style of architecture than most of the other bridges, and stands out amongst them, both because of its size and appearance. Because it is part of the interstate system, it is used for vehicles, and only for vehicles. No moonlight strolls along this bridge! It was also built much later, and because it was an interstate bridge (and thus part of its justification for existence was to improve military mobility) it was built up much higher, so that it wouldn't need to be a draw bridge. So the bridge does not have the intricate truss work of the road bridges, instead being a very utilitarian piece of work, made out of concrete and hovering over the city. There is a chance that in Portland's current climate, which is much more conscious of "urban livability", and has something of an anti-car attitude, that a gigantic freeway bridge like this could not be built. (And indeed, the next freeway bridge to be built, the Fremont Bridge, was designed to be much more aesthetically pleasing).
With all that being said, the bridges of Portland are not meant solely for the purposes of giving hipsters scenic spots for kissing. They are meant to carry traffic, and in the case of the interstates, to carry a lot of traffic, much of which is not even destined for the area. And the bridge does accomplish that, its two decks carrying traffic efficiently up and over the downtown area. Also, the engineering of the bridge, even if it isn't an arch or suspension bridge is still impressive in the scale, and just the fact that it works. The view from the top of the bridge, even though it can not be savored, is still something that should be seen.
The site www.bridgehunter.com has been a rich source of information about bridges recently for me, including this one.