This year marked the opening of Helix at Sweden's Liseberg, a massive 4,500+ foot long launched coaster design by Mack Rides. The coaster has received high marks so far this year, due to its innovative design and interaction with several other rides at the park.
Almost all major roller coasters go through several phases of design, but it is quite rare that any park will show off "what could have been." However, that's exactly what Liseberg did, showing off the evolution of the design that became Helix.
Several years ago the park had decided on a tall mega coaster that would tower over the park's hillside, utilizing much of the same space as Helix now does. The first design of that ride is seen above, and while the bulk of the layout isn't too inspired, look at that first drop! Wow!
The park continued to tweak the mega coaster design, shifting things around a bit and adding more action to the ride. That also meant going even higher than before (though no statistics for height are given). Check out the first drop planned on this one, a twisting fall that looks a bit mouth watering.
Eventually the park decided that height wouldn't be the focus of their new ride, and added in two launch sections and covered even more of that hill with track... and eventually created Helix. This neat video shows off that process, with the many changes in Helix's layout along the way. Pretty cool stuff!