I feel like the Troll A platform should be in there somewhere. It may not be pretty to look at, but it's Norway's tallest structure and the biggest object ever moved, which has to count for something. Plus it represents the oil era very well. Then again, it might be more of an engineering wonder than an architectural one.Here is what I think most would list as the seven architectural wonders (or at at least the most iconic sights) of Norway.
If I were to rank the engineering wonders of Norway, it would be something like this:
1. Ulla-Førre hydropower complex. A massive webwork of interlinked lakes, ponds, tunnels and pipes covering more than two thousand square kilometers, feeding power plants generating some 7.5 % of Norway's entire electricity production. Not very picturesque, though (and most of it is underground), so here's a picture of one of the dams.
2. The aforementioned Troll A oil platform. 472 meters tall, weighing 684,000 tons, it is the tallest and heaviest object ever moved. It pumps gas from 40 wells on the seabed off the Norwegian shore.
3. The Bergen railroad. Until the start of the 20th century, most transport between Norway's biggest cities happened by ship, as the mountains were considered impassable in winter. I've read somewhere that polar explorer Fridthiof Nansen is considered among the first to travel the overland distance in winter. Then in 1894 Parliament decided to shell out a sum roughly twice that of Norway's national budget to build a railroad across the mountains. It opened in 1909, finally giving Oslo and Bergen a year-round overland route.
4. Langeled pipeline. Another one from the gas industry, this time the 1166 km long gas pipeline sending natural gas from Norway to the UK along the seabed, by way of the offshore gas fields. Building it was one of the most complex engineering projects ever undertaken in Norway.
5. The Lærdal tunnel. Currently the world's longest road tunnel at 24.5 km in length. It ties together Lærdal and Aurland somewhere on the west coast, with a combined population of... uh, less than 4000 people. Yay for the oil-boosted economy! More importantly, it is part of the E16 highway, considered by some to be the main road between Oslo and Bergen. Its construction also finally provided a ferry-free road link between the two cities that was sure to be open in winter. This happened as late as in 2000, by the way.
6. The Hardanger bridge. It's a pretty long suspension bridge, and very narrow because Norwegian roads don't need to have that much capacity.
7. The Holmenkollen ski jump. It might not be the biggest or most attended ski jump in the world, but it is very iconic and is a landmark visible at long distances around Oslo. It was also Norway's most visited tourist attraction, at least until they stopped making the lists because of the high uncertainty in the data. It's a fair bet to say most visitors don't come for the ski jumping competitions (as those happen outside the tourist season), but it manages to be very photogenic in summer too! For the record, Austrian Andreas Kofler currently holds the ski jump record in Holmenkollen, at 141 meters.
All pictures from Wikipedia.