Dr. Wily's Robot Manufacturing Plant

Dr. Wily's Robot Manufacturing Plant, known (roughly) as "Dr. Wily's Giant Factory of Robots" (Ｄｒ．ワイリーのロボット大工場) in Japan, named Castle Wily (ワイリーキャッスル) in Mega Man Powered Up, is a robot factory constructed by Dr. Wily in the Pacific and his fortress in the first Mega Man game.

Wily Stage 1
The first stage from Dr. Wily's factory. Mega Man begins outside the base at daylight and uses Super Arm to open a path inside. The Magnet Beam is required to pass from one area.

Enemies in Mega Man:
 * Big Eye
 * Flea
 * Foot Holder
 * Killer Bullet
 * Boss: Yellow Devil

Enemies in Mega Man Powered Up:
 * Big Eye
 * Crazy Cannon
 * Crazy Razy
 * Flea
 * Shield Attacker
 * Sniper Joe
 * Boss: Yellow Devil

Wily Stage 2
The second stage appears to be in a long open area above the base.

In Mega Man Powered Up this is the third Wily stage, and it takes place at night. The player has a rematch against the eight Robot Masters.

Enemies in Mega Man:
 * Bombomb
 * Blader
 * Blaster
 * Octopus Battery
 * Screw Bomber
 * Cut Man
 * Elec Man
 * Boss: Copy Robot

Enemies in Mega Man Powered Up:
 * Blaster
 * Killer Bullet
 * Met
 * Octopus Battery
 * Screw Bomber
 * Boss: CWU-01P

Wily Stage 3
The third stage, a small vertical area followed by a long horizontal area filled with water.

In Mega Man Powered Up this is the second Wily stage.

Enemies in Mega Man:
 * Killer Bullet
 * Peng
 * Octopus Battery
 * Screw Bomber
 * Boss: CWU-01P

Enemies in Mega Man Powered Up:
 * Blaster
 * Count Bomb
 * Octopus Battery
 * Picket Man
 * Watcher
 * Rematch against the eight stage bosses (Cut Man, Guts Man, Ice Man, Bomb Man, Fire Man, Elec Man, Oil Man, Time Man)
 * Boss: Copy Robot

Wily Stage 4
The last stage. The area has several spikes, and many Guts Men can be seen in one Has a Yashichi before the battle.

The Yashichi is not present in Mega Man Powered Up, possibly because the boss rematches were replaced to the third stage.

Enemies in Mega Man:
 * Screw Bomber
 * Watcher
 * Rematch against Bomb Man, Fire Man, Ice Man, and Guts Man
 * Boss: Wily Machine Number 1

Enemies in Mega Man Powered Up:
 * Blaster
 * Screw Bomber
 * Octopus Battery
 * Boss: Wily Machine Number 1

Other media
Dr. Wily's fortress in other media related to the first game.

Mega Man
In Archie's Mega Man comic series, Dr. Wily's Robot Factory has the same appearance of the Wily Castle from Mega Man 2. It is a facility made of steel and concrete with a skull motif. It is enormous in size, cold, gloomy, and full of noise as many machines work to pump out robots of all imaginable shapes and sizes. The size and layout of the factory would allow it to be a veritable fortress in its own right, but rumor has it that Wily has been overseeing numerous renovations to the exterior of the plant, making it far less welcoming to guests than it had been in the past.

Mega Man Megamix
In the manga Mega Man Megamix, Dr. Wily uses a large pyramid-like moving fortress to attack the city in the story "The Birth of Mega Man". When Mega Man defeats Elec Man with the Rolling Cutter, the fortress' reactor become unstable, and would cause a large explosion if not stopped. Elec Man reluctantly reveals he had to control the reactor's energy, and now it's out of control, but Mega Man could probably find something to stop it in the control room. Mega Man proceeds to the room and faces Bomb Man, Fire Man, Ice Man, and Guts Man in the way. In the control room, Mega Man is caught by the Yellow Devil, and Wily reveals himself. However, Mega Man breaks free of the Yellow Devil's grasp with the Super Arm, and tries to attack Wily, but his arm is sliced off by a mysterious robot covered in a robe. Seven other robots, all in robes appear, and Wily explains he didn't intentionally plan to use Light's robots to take over the world, but simply use them as a distraction to plan for his robots. Wily gets away, and the fortress is about to explode. But then, Dr. Light shows up, and shows him he managed to get his robots under his control again, and they manage to stop the unstable reactor, preventing its explosion.