There are four locations out of 12 locations that I've not found. Most likely they are in areas where I don't ride frequently, so I don't recognize them. Three of them are buildings. One is a tree, and I've not found the correct one yet. There is quite a lot of trees around here, so it might take a while. The correct results are available on the website and a quick search would tell me where they are, but that would ruin my fun.
I had taken photos of four of the locations and most of them have been mentioned at the blog, too: a bike bridge, Hydro Dam Bridge, the combined heat and power plant, and the water tower (not sure if this has been on the blog?)
Sightseeing tower. Last week I took photos of the Chapel of St. Luke, a statue and Ouluhalli (an indoor sports arena). These were locations I knew and they're easy to find.