Nocturne

The Nocturne (ノクターン) is the central stronghold and capital of Imperator Ix and the Nocturnus Clan echidnas. It appears as the final area in Sonic Chronicles: The Dark Brotherhood and is used in Mario &amp; Sonic at the Olympic Winter Games as a course for the Dream Bobsled event.

Pre-Cage
During the Nocturnus Clan-Knuckles Clan war 4000 years ago, Nocturne apparently functioned as the capital of the Nocturnus Clan. The Nocturne in its original form is shown briefly during a movie sequence in Sonic Chronicles, and appears somewhat similar to the echidna pyramid-cities ruled by Pachacamac in Sonic Adventure; albeit more advanced, with glass windows and waterwheels. This picture matches with Ix's comment that the Nocturnus "believed in science and industry, and we flourished". It is stated by Nestor the Wise that the Nocturne housed (and still does) the Nocturnus Clan's Gizoid-production labs; as such, Emerl must have been 'born' there.

Post-Argus
After the near-total destruction of the Knuckles Clan at the hands of Perfect Chaos, the Nocturnus echidnas "nearly colonized the whole world". However, just as complete global conquest was within their grasp, the Argus Event occurred. Sonic Chronicles shows the Nocturne being torn out of the earth into a portal to the Twilight Cage. This was a violent event, scattering wreckage from the echidnas' fortress all across the pocket dimension. Nonetheless, under Ix's leadership, the Nocturnus were quick to recover and adapt. Trading and fighting with the other races of the Cage, the echidnas acquired fantastic new technologies and tactics. The Imperator states "We had to change and adapt and become who we are today. We had to become perfect!" The Nocturne's appearance changed drastically, from an idyllic fusion of nature and clockwork, to a brooding techno-fortress, complete with laser turrets and shield generators. It is in this form that Sonic and friends find the stronghold during Sonic Chronicles.

Trivia

 * The music used for Noctourne is a remix of the final boss battle theme for Sonic 3 and Knuckles.