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. The first base, only seen in Mega Man Zero, is an old building set underground. After the damage done by Neo Arcadia, the Resistance moved to a new base in Mega Man Zero 2, to which they operate from for the rest of the war.

The Resistance Base is a shelter for injured 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 Reploids were killed during the search, but Ciel, the only survivor from the search team, was able to find Zero. 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, and two gates in each side, one to the Desert and other 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 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 a room (TRANCE) with the base's Transerver, used to teleport to other known 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 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.

New Base
The second base is more detailed and organized compared to the previous base. Some of its features are a command room (with a teleporter in it), Ciel's room, eight barracks, a maintenance room, among other things, and labels to present what is the room above each door. The base contains an elevator in the center. Its seems to be located inside of a mountain or cliff adjacent to a body of water (judging by the presence of a harbor).

Although the base is new (according to Elpizo, construction was finished just as the second game began), Neo Arcadia is fully aware of its location, since Sage Harpuia dropped Zero in front of the base, and after Operation Righteous Strike, Neo Arcadia attempted to destroy it with an aerial strike.

Floors

 * R - Roof with two towers equipped with cannons to scan the area for Neo Arcadians.
 * 5 - Arsenal where the cannon shells are stored. There's also a ladder for each tower.
 * 4 - To the left of the elevator is a lookout where Hirondelle watches the area and a storage room (ROOM) with Pic. On the opposite side is a maintenance room (ROOM) where Rocinolle treats injured Reploids and the command center (CMD) with a teleporter operated by Rouge and Joan where missions are taken. The command room leads to a corridor with two more rooms, Cerveau's lab (LAB.) and Ciel's lab (CIEL). Alouette and Doigt are in this floor.
 * 3 - Area where Andrew strolls by on the left. In the second game there is a dorm (ROOM) to the left, but in the third game it was omitted and will only appear with Mod Card #25. To the right there is a hall (ROOM) that has four rooms (03A, 03B, 03C, 03D) that serves as the soldiers' barracks. Soldiers rescued in the Forest of Dysis stay in this floor.
 * 2 - To the left there is a hall (HALL) that resembles a locker room with 10 lockers, 3 tables, and 19 boxes. To the right there is another hall (ROOM) that, like the 3rd floor, has four rooms (02A, 02B, 02C, 02D) that appear to be living quarters. Brainwashed soldiers rescued in the Crystal Cave mission stay in these quarters. Hibou is in this floor in the third game.
 * 1 - Contains a data library (1F-A), and a storage room (1F-B) and a harbor where supplies comes in. Hibou, Perroquiet, Autruche, and Menart are in this floor.

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.