Do NOT go see the priestesses until you're ready to advance the plot and move on to the next dungeon. The airship will become unavailable for normal travel once you do. While a black chocobo still gets you most places, it's slower and, between the inability to cross mountains and the lack of a wider view, harder to navigate.

The screen dims.

The reactions of the priestesses range from confused...

...through cautionary...

...and repetitive...

...to helpful.

With permission to enter granted, the guard finally allows access to the largest of the treasure chambers. Contents include various healing items, a Greatbow and assorted arrows of the types sold in town (which would have come in handy earlier), and even a Silver Apple (JP version only; the others have an Elixir instead).

Cain's airship approaches immediately after liftoff.

The airships ascend....

...and the party ends up in an area with a high-tech look. There's no sign of Cain, Rosa, or anyone else.

Note that you can leave the tower by returning to where the party entered, but the airship won't fly anywhere but here until the dungeon is cleared.

The Marionettes in this tower will summon more minions if you kill off all other monsters. It's a good place to farm experience if you want to.

Many (but not all) of the monsters here are weak against Flame. Equip Yang accordingly. There are also quite a few chests here containing elemental Flame weapons and armors for Cecil and Cid. The rule of thumb for this game is that anything with "fire" or "flame" in the name is good against anything Ice, but poor against Flame. The new equipment is usually a step up, but be careful of that weakness. Specifically, there's a chest on the 2nd floor containing a Flame Dog. Switch equipment for that if you don't like taking excessive damage, then enjoy the Flame Sword you win for your efforts.

You'll find Yang's Hell Claw on the 5th floor. Though lacking any elemental or racial traits, it's more accurate than his previous claws and may inflict Poison status. Cid's Earth Hammer is also here. A reasonably strong Flame weapon, its true power lies in the item effect: Use it to produce a weak, but still helpful, Quake spell. There's a Priest Robe for Tella, too.

Also on the 5th floor, slightly past the save point....

Boss time! Dogu, the tall one in back, will periodically cast Reflect on Magu, the fat one in the middle, with the following line:

Magu responds with the following as she attacks a random character:

Ragu, the little one in front, follows up with a spell on Magu, cycling between Fira, Thundara, Blizzara, and Bio, in that order:

Things start falling apart when they aren't all present, though. In addition to being the cornerstone of their Delta Attack, Magu will fully revive the others after a turn delay if either of them goes down, so she's the priority target, even though she has nearly twice the hit points of the others. Once Magu is out of the picture, Ragu is reduced to casting Fire, Thunder, Blizzard, and Poison, while Dogu cycles between Confuse, Berserk, Slow, and Cura (on herself). Confuse rarely works, and everything else is negligible at this point. Cecil and Yang should attack, Cid can either attack or use his hammer for Quake, and Tella is on buffing and healing duty. All in all, this isn't that difficult of a battle.

The way to the 6th floor is clear. Cain and Gobeza himself are on the far side of the room.

You really ought to see this coming, but just in case... make sure to unequip Tella now if you want anything he's using.

Tella pushes forward, shoving Cecil out of the way, and gets in Golbeza's face.

Battle commences, Tella versus Golbeza. Tella opens with Bio and Figa, which deal piddling amounts of damage (mostly because of a spell multiplier glitch that only affects scripted battles).

Undeterred, Tella follows with Thundaga and Blizzaga, which inflict similarly meager amounts of damage.

Tella casts Meteor. In addition to being approriately flashy, it typically manages to inflict 9999 damage despite the damage glitch (Golbeza's 4x weakness to Holy for this battle helps with that, but it's quite a powerful spell regardless).

Golbeza is weakened, but considering that Tella just cast 209 MP worth of magic despite having only 90 MP, he's in worse shape. Oddly, Cain collapses too.

Golbeza starts to leave.

Golbeza lightning bolts Cecil across the room, starts to approach, and then suddenly stops.

Golbeza exits, leaving Cecil rather confused.

And Tella is gone.

The door is locked, so I suppose we'll check on Cain.

Cain leads them upstairs, where Rosa is still tied up, with a blade (or iron ball) looming over her head.

The implement of death begins to fall, and Cecil snatches Rosa out of the way just in time.

Cain looks ashamed, while Cecil and Rosa get in each other's personal space.

Cecil and Rosa break apart, and we never see their shared sprite again. A pity.

Cecil hesitates briefly, then:

Before doing anything else, give Rosa some equipment! You should have a bow and some arrows handy (or a Healing Staff), plus Tella's old equipment and the Gold Hair Ornament from Mist. Cain is already outfitted with a Wind Spear and full set of Mithril armoring, so he's fine. Then heal anyone who needs it and rearrange the party if you like. Head out of the tower only after that, because....

She attacks, and that's why you should get ready before trying to leave. Barbariccia has no elemental weaknesses, but she does have some tricks up her sleeve. Shortly after combat begins, she goes into a whirling mode that gives her considerable evasion (greatly weakening the effectiveness of most physical attacks) and near immunity to all forms of magic. Additionally, as long as the whirlwind lasts, she'll cast Tornado AND use Fingertip (Gradual Petrification (1/3)) every turn. Attack despite her defenses for a clue:

The EasyType and NA versions apparently decided that wasn't obvious enough, so they changed it:

Hitting her with Cain's Jump breaks the whirlwind, resetting her physical defenses to nonexistent and her magical defenses to moderate. She attacks immediately upon resetting state, then again her next turn, then goes back into the whirlwind after a delay. If you want this battle to go well, keep her out of the whirlwind as much as possible. Hitting her with Slow once or twice when she's not spinning is also a big help, as is Berserk on Cid and Yang (and Cecil, if you don't mind giving up use of his White Magic), though the extra messages every time they attack during whirlwind mode get annoying.

The tower shakes violently as Barbariccia disappears.

Incidentally, you might not have even realized Rosa knew Teleport. She doesn't have it until rejoining just now, and even if you had noticed, you can't cast it here yourself anyway.

The party warps out of the tower and appears safely in...

So, not only have we been given the impression that it's not unusal for Rosa to visit Cecil late at night, but it she would seem to be familiar enough with his bedroom that it's her choice in destination for an emergency teleport. The writers can't outright say they're sleeping together regularly... but it's pretty obvious.

Consider raiding Eblana Castle at this point if you didn't already. It's still challenging, but having a full party with higher levels, slightly better equipment, and a dedicated White Mage could help.

Clues from the earlier world tour point here. The villagers spoke of being descended from dwarves who came from a concealed land under the mountains. Putting together the mention of a sun called "magma" and the legend that the way to their homeland will be opened when the stone of the sun is returned there, Cecil tries dropping the Magma Stone in the immesurably deep well.

The stone falls a very long way, and then....

With a great rumbling, the nearby mountain bursts open, revealing a large hole leading to untold depths!