Castle That Never Was

Nothing's Call

Nothing's Call (虚無への誘い Kyomu e no Sasoi?, literally "Invitation to Nothingness") is the lowest known area of the Castle That Never Was, acting as a sort of "basement". It appears to be the only entrance into the castle for people who are not members of the Organization. Sora, Donald, Goofy, and King Mickey enter the castle here, Sora calling for Kairi. King Mickey silences him, reminding him that they are in the stronghold of the enemy. He rushes off to find Ansem the Wise. They are soon attacked by Nobodies but make it to the next area.
It is also here where Roxas fought Saïx when leaving the Organization in Kingdom Hearts 358/2 Days.

Soundless Prison

The castle has a number of dungeons somewhere in the lower sections of the castle. Here, Kairi and Pluto are imprisoned in one of the cells. Kairi is briefly visited by Saïx who explains to her that she will be the bait used to make Sora slay more Heartless in the plan to complete Kingdom Hearts. However, Naminé appears through a portal in the cell and helps Kairi and Pluto escape. Strangely, the bars of Kairi's cell were far enough apart that she could have easily escaped before being freed by Naminé. However, it could be possible that the Organization foresaw this and placed a barrier over the bars to prevent this.
This area is not accessible in Kingdom Hearts II, and is only for storyline purposes.

Crooked Ascension

Crooked Ascension (歪みを貫く柱 Yugami no Tsuranuku Hashira?, lit. "Distortion-Bridging Pillar") is an area of the Castle That Never Was. It seems to be a giant elevator that ascends and descends without actually appearing to do anything. While inside, Sora, Donald, Goofy and Riku may be attacked by either Samurai or Dragoon Nobodies if going to Nothing's Call or Twilight's View respectively.

Twilight's View

Twilight's View (黄昏から望む場所 Tasogare kara Nozomu Basho?, lit. "Place Viewed from Twilight") is a location in the Castle That Never Was. It is a stairway leading to the next floor of the castle. Sora can meet a Moogle here and synthesize new items. According to a flashback in Kingdom Hearts II Final Mix (which takes place before Kingdom Hearts, Kingdom Hearts: Chain of Memories, and Kingdom Hearts II), Zexion and Xigbar discussed Xemnas's frequent visits to the Chamber of Repose and the discovery of Castle Oblivion here.

Hall of Empty Melodies

Hall of Empty Melodies (虚ろなる旋律の空間 Utsuro-naru Senritsu no Kūkan?, lit. "Space of Empty Melodies") is a large room in the Castle That Never Was, located in The World That Never Was. A large platform makes up the room with large walls facing either side of it. Several primary events happen here in the final battle involving Sora, his companions and the surviving members of Organization XIII. Here, Sora, Donald and Goofy encounter Saïx, who informs them that due to the completion of Kingdom Hearts, the Organization no longer needs them. Kairi then appears on an overhead balcony and leaps down with Riku, in the form of Xehanort's Heartless, to help Sora. At this time, Maleficent and Pete also arrive in the castle.
Xigbar eliminates all of the Heartless so he can take on Sora himself, but the ensuing battle culminates in Xigbar's death. Sora, Donald and Goofy head off to the upper level of the room where Sora has an emotional reunion with Kairi and Riku. Sniper and Assassin Nobodies appear during navigation through the room.
In Kingdom Hearts 358/2 Days, this room is where Roxas must complete Mission 10 and Mission 71; Mission 33 is also performed here.

Naught's Skyway

Naught's Skyway (虚空を辿る道 Kokū o Tadoru Michi?, lit. "Road Following Empty Space") is an area in the Castle That Never Was, in The World That Never Was. It is a small outside path in a high section of the castle. This is where Mickey finds DiZ, who is revealed to be Ansem the Wise, being attacked by Nobodies. After they are defeated, the two walk off with Ansem's encoding machine. Sora and his companions pass through here in order to find King Mickey and Ansem the Wise.

Proof of Existence

Proof of Existence (存在の証 Sonzai no Akashi?) is a room in the Castle That Never Was. Sora, Donald, and Goofy pass through here after reuniting with Kairi and Riku. Kairi felt uncomfortable in the room, saying it felt like a graveyard. The passage through the room was blocked, and Sora was forced to defeat Luxord and Saïx by entering their portals before they could pass through.
The room was characterized with panels on the floor representing the members of Organization XIII (excluding Xemnas and Xion), indicating their title, weapon, and rank by going from left to right. The panels of the Organization members who had died were colored red and damaged. By the time Sora and his friends arrived, most of them were in this state, with only three panels left undamaged. Zexion's panel was so damaged it was unable to show his weapon. After Roxas left the Organization his panel was most likely destroyed, but as Roxas lives on in Sora, his panel is still blue.

Havoc's Divide

Havoc's Divide (混沌の狭間 Konton no Hazama?, lit. "Ravine of Chaos") is an area in the Castle That Never Was, in The World That Never Was. It appears to be Luxord's chamber, as he attacks Sora and his companions here. The area is sloped and leads to a steep drop downwards. Here, Riku reveals DiZ is actually Ansem the Wise. Luxord appears and traps Riku, Kairi, Donald and Goofy in his cards and challenges Sora to a duel. After a close fight, Sora defeats Luxord who fades into darkness. Sora's friends are returned.

Addled Impasse

Addled Impasse (惑わしの空間 Madowashi no Kūkan?, lit. "Bewildered Space") is an area in the Castle That Never Was, in The World That Never Was. The chamber is large in size with a clear view of the Kingdom Hearts moon. This area appears to be where Saïx stays, due to his presence, and the fact that when Sora and his companions arrive, they see Saïx looking up at Kingdom Hearts (which relates to his moon element). Here, Sora and company battle Saïx and emerge victorious. Saix is fatally wounded, and fades into darkness while asking Kingdom Hearts where his heart is. Riku also reveals Roxas is actually Sora's Nobody after the battle.

Naught's Approach

Naught's Approach (虚空を目指す道 Kokū o Mezasu Michi?, lit. "Road Aiming for Empty Space") is an area in the Castle That Never Was, in The World That Never Was. It is an exterior passage which leads to Xemnas's tower. Here, Kairi and Naminé escape from the prison cells of the castle and are confronted by Saïx on the stairs, but are saved by Riku. Later, Ansem the Wise and King Mickey set up Ansem's machine so he can digitally absorb Kingdom Hearts. Sora, Riku, Kairi, Donald and Goofy make their way up to the area after viewing them from Havoc's Divide. Ansem realizes the machine cannot contain Kingdom Hearts and monologues what a fool he is. Sora and his friends arrive, as does Xemnas who has a "heart-to-heart" with his former teacher. Ansem tells Xemnas his plans will fall, and apologizes to Roxas and the King before being engulfed by his exploding machine. The explosion damages Kingdom Hearts and restores Riku to his normal body.

Ruin and Creation's Passage

Ruin and Creation's Passage (破壊と創造の回廊 Hakai to Sōzō no Kairō?) is an area in the Castle That Never Was, in The World That Never Was. It is the biggest area in the castle with platforms floating in the air. Invisible paths can be used to reach each platform and eventually navigate to the other side. Sora, Riku, Kairi, Donald, Goofy and King Mickey make their way across, battling Nobodies on the way. Kairi spots endless Heartless streaming in through the windows towards them. Maleficent and Pete appear and send the group to take down Xemnas, Maleficent reminding Sora and King Mickey that the castle will be hers. Sora tries to help them, but King Mickey dissuades him.

Altar of Naught

The Altar of Naught (虚空の祭壇 Kokū no Saidan?, lit. "Altar of Empty Space") is an area in the Castle That Never Was, in The World That Never Was. It is a giant tower that is high above the rest of the castle. Xemnas often comes here to speak to Kingdom Hearts. Sora, Riku, Kairi, Donald, Goofy, and King Mickey arrive to see Xemnas lamenting over how his plans have failed, asking them to find more hearts. They refuse and they converse about how Xemnas cannot show emotions. Xemnas battles Sora but is defeated. Xemnas fuses with Kingdom Hearts and leads the group into a battle against him. He is defeated again and apparently fades into darkness. Trapped in the world, the group seem helpless, until Naminé opens a portal to Destiny Islands. Naminé and Roxas join with Sora and Kairi at long last. Everyone passes through except Sora and Riku who end up trapped when a giant Nobody dragon flies in and slams into the side of the tower. Sora and Riku slide down the tower which tilts sideways. Riku spots an odd aircraft and hops onto it, Sora following. They fly after the dragon as the tower collapses.

Memory's Contortion

Memory's Contortion is a strange, wavering illusion of the Memory's Skyscraper that Xemnas draws Sora into to battle. This area was for battle purposes only and cannot be visited after defeating Xemnas.

Where Nothing Gathers

This room, known to Organization members as The Round Room, and inaccessible by any means other than by corridors of darkness, is a circular room containing throne-like chairs ranging in height, where the Nobodies of Organization XIII can gather and discuss developments and for Xemnas to give out orders. There are thirteen throne-like chairs that are rather tall in height, each occupied by a member of the Organization.
Tetsuya Nomura himself has stated in an interview that the height of each throne is just a gameplay mechanic.
-During the meetings, the members of Organization XIII are sitting in chairs. Is the height of these chairs determined by things like their skills and abilities?
Nomura: No, the height of the chairs is not fixated, they move. That is to say, the height is up to each person. The leader, Xemnas, is always the highest and to be at the same height as him would have a pretty bad feeling, so the other members wouldn't do that. (laughs)
The seats are arranged in a circle with Xemnas at the prominent seat. At Xemnas's left are the odd numbered members, and to his right are the even numbered members, increasing in numerical value up until number 13, Roxas's seat, which is across from Xemnas's. The "fourteenth member", Xion, has no throne as she was neither a true member nor even a real Nobody, but a replica, meant to fuse with Roxas, thus the reason for the group's name remaining as "Organization XIII".

The Grey Area

The Grey Area (闇と光を紡ぐ庭 Yami to Hikari o Tsumugu Niwa?, lit. "The Garden that Interweaves Darkness and Light") is a room in the castle that serves as a lounge for the Organization's members, as well as the place where the members receive their mission briefings from Saïx. The room is wedge shaped with one wall made entirely out of a giant window, out of which Kingdom Hearts can be seen floating in the distance. The room has couches and tables spread around it, and Organization members are often seen lounging about between missions. There is also a Moogle here, dressed in the Organization coat, that allows Roxas to synthesize panels and access a shop that uses heart points as currency.

Computer Room

In Kingdom Hearts 358/2 Days, it has been revealed that the castle has a room with a computer that seems to contain information on all the Organization projects including the Replica Program and Castle Oblivion.

Library

In Kingdom Hearts 358/2 Days, it was revealed that the Castle contained a library filled with literature on various subjects. One book the player's attention is drawn to is one seen being read by Axel, titled "The Truth about Naminé," composed by Vexen. This one, unvoiced cutscene in Kingdom Hearts 358/2 Days has been the library's only appearance.

Bedrooms

Each of the members of the Organization have individual bedrooms in the castle. The rooms are white with metal-like walls, with a single bed with the headboard shaped like the Nobodies' symbol and a window showing the heart-shaped moon of Kingdom Hearts.