Resistance Base

Resistance Base (レジスタンスベース), as its name suggests, is the base of operations of the Resistance in the Mega Man Zero series, set in an old underground area on the Old Surface City. After the damage done by Neo Arcadia in Mega Man Zero, the Resistance moved to a New Resistance Base in Mega Man Zero 2, to which they operate from for the rest of the war.

The Resistance Base is a shelter for Reploids who are suspected of being Mavericks. Although they try their best to survive against Neo Arcadia, they know that they were fighting a losing battle. As a last resort, the Resistance searched for the legendary Reploid Zero in hopes that he will help them. Many Resistance soldiers were killed during the search, but Ciel, the only survivor from the search team, was able to find Zero in a Forgotten Laboratory. Zero saves Ciel from the Neo Arcadian forces, and she takes him to the Resistance Base. In the base, Zero hears about the conflict between the Resistance and Neo Arcadia and agrees to help, going in several missions.

Some time later, Neo Arcadia sends troops commanded by Hanumachine to attack the base. The Resistance is unable to hold them out, and the base suffers heavy damage. All survivors abandon the base with an evacuation transport.

Floors

 * The surface is a wasteland area containing abandoned buildings, an elevator and stairs to the Resistance Base, stairs to the Subway Ruins, and two gates in each side, one to the Desert and other to the road leading to the Disposal Center. A Transerver is located in the building near the Desert gate. In one of the missions, Neo Arcadia sends Hittite Hottide to destroy the Base, deployed at the entrance to the Disposal Center. Regardless of the outcome, Neo Arcadia will later send troops led by Hanumachine that are successful in breaking through the gate's shield and invade the base.
 * Basement floor 1 has two rooms and stairs to the surface. Alouette strolls in this floor. One of the rooms appear to be a mess hall and has the Reploid Dande. Two of the three Reploids rescued from Aztec Falcon in the Disposal Center will settle in this room. The other room (ENERGY) is the Energy Room, a warehouse where Energy Crystals are stored. Zero fights Hanumachine in here. Also, the male soldiers rescued from Blizzack Staggroff will stay in the warehouse.
 * Basement floor 2 has two rooms. The "DATA" room is where Zero can talk with Ciel to start missions and save game data. "Sci. CIEL" is Ciel's room, located behind Ciel in the Data Room, which will be locked unless Zero is at rank A or S; inside is a Cyber-elf. One of the Reploids rescued from the Disposal Center will stay in this floor.
 * Basement floor 3 has the Trance Room (TRANCE) with the base's Trans Server, used to teleport to other known Trans Server ports and adjust Cyber-elves. There is one soldier stationed outside the room.
 * Basement floor 4 has two empty rooms, with Andrew walking around near the elevator. The female soldiers rescued from Blizzack Staggroff will stay in this floor.
 * The last floor contains two rooms, one the engine Control Room that makes the elevator work. The engineer Cerveau modified this room to be his laboratory. Hibou is resting in this floor, blocking the path to the second room, and will only move if he receives 250 EC. The second room contains a Cyber-elf. The survivor pilot rescued from Anubis Necromancess mission will stay in the same room.

Enemies

 * Cannon Hopper
 * Gli-Eye
 * Pantheon Guardian
 * Pantheon Warrior
 * Boss: Hanumachine

Resistance Trailer
The Resistance Trailer is a mobile unit of the Resistance, constructed by Ciel so that a part of the organization can move to wherever they're needed. At the beginning of Mega Man Zero 4, the trailer intercepts a Caravan, and they protect it from the forces of Dr. Weil trying to bring back the humans. After that, the trailer follows the Caravan to Area Zero, where they spend the rest of the game protecting the area and its populace from Operation Ragnarok.

The Trailer comprises three connected, hi-tech box trucks, one larger than the other two. The larger truck has two rooms, housing the Command Center, occupied by Ciel and Rouge, and Cerveau's lab. The other two cabins mainly consists of a bedroom apiece, one occupied by Alouette and another by Hirondelle; however, there's a computer in Alouette's room that can help Zero upgrade his Cyber-elf.