The Colossus of Rhodes is a Wonder that requires Sulfur to build.
It shows very nicely the different construction phases as progress is made in checkmarking one resource bar after another.
Like the Lighthouse, the Colossus may be placed in water only. Do not place on land.
Update: And a few Mountain LocationsEdit
It has been found that the Colossus in addition to the waters around the island may be, if carefully aligned, placed into a limited few mountain locations. One of these locations is the mountain in the back right corner. This is widely considered a bug and not intentional on the part of the designers.