|This article contains information that does not coincide with the main series canon.|
Nightmare's Fortress is a large space station located 900 light years away from Planet Popstar. It is home to the evil eNeMeE and headquarters for his company, Nightmare Enterprises. According to what Sword Knight says in Cappy Town Down, the fortress is where all of Nightmare's monsters and other inventions are born. The fortress' first appearance was also in said episode.
The fortress is surrounded by many Destroyas, all of which protect the fortress inside and out. Its exterior is covered in structures and skyscrapers, as well as many gun turrets and many trenches. Its distinctive, huge red eyeball on its front that looks strikingly like 0's.
The interior is futuristic, with many trenches, elevators and monorail-like trolleys. Not only is the interior protected by Destroyas, but also by laser guns and Air Riders. At the heart of the fortress' interior lies the command center, where the members of Nightmare Enterprises control the fortress. The command center is also where they, most specifically the N.M.E. Sales Guy, deliver monsters and other items to their customers from. The fortress has many locations besides the command center, among them the Monster Training School and Nightmare's chess board-like lair.
The fortress was finally destroyed at the end when Kirby's crew planted a time bomb on the monster transmitter within the command center, which detonated not long after all of the crew escaped together, which blew up the whole fortress from the inside. As the fortress exploded, the N.M.E. Sales Guy can be heard screaming (this was edited out of the dub), suggesting that he did not survive the blast. The fortress' destruction, marks the end for Nightmare Enterprises, meaning King Dedede no longer has any way to buy himself more monsters for whatever reason.
- When the Halberd is flying along the trenches of the fortress's exterior, it is a reference to the 1977 film, Star Wars. The fortress's exterior also bears resemblance to Cloud City, which appeared in the movie following Star Wars.