This was my first visit to Sellwood Park, so I can't attest to how it has changed over the years, but judging from the minimal wear and tear to them, most of the structures appear to be on the newer side (post-year 2000). There are several climbing structures, two sets of swings, a tall retro-looking (but newer) slide, a set of four teeter-totters, and a merry-go-round-ish thing that's reminiscent of a fat hula hoop. This seemed to be the most popular attraction among the kids when I was there, but my friend tells me that several years ago, her friend (an adult) tried standing on it and wound up with a broken ankle.
Sellwood Park is located at SE 7th Avenue and Miller Street in Portland.