I went into the Gregminster area, right before the final battle with Yuber, and - big surprise - it was all like it was left (Gregminster, Lenankamp, Rockland). You can't enter Gregminster under any circumstances, because there is a script that will kick you out of the city, even if you warp to any location of the city with this code.
I entered Magician's Island and as soon as I landed on the shore, Futch always takes the whole party "back" to Gregminster. If you happen to bring Cleo, Pahn or Gremio along, they are visible. Otherwise, only Tir and Ted are shown. The flight sequence with Black happens at night, like the one you'll see at the Dragon's Fortress. Back in Gregminster, I walked through the throne room in the back area, where you go at the end of the game normally. Surprisingly, the whole castle can be explored by daylight (bright colors, castle music, treasures and save crystal are missing), only the garden at the top shows a dark sky. One of the stairs is a one-way here, though, so there is no way out.
There is one additional room between two areas, which you can't reach normally, and it's not the one shown in the sequence when Ted meets Windy in the castle.
The secret room lies beyond this passage:
![Image](http://www.suikosource.com/celes/images/wallwthroughwalls/gregminster1.jpg)
Two storied hall:
![Image](http://www.suikosource.com/celes/images/wallwthroughwalls/gregminster2.jpg)
Upper floor:
![Image](http://www.suikosource.com/celes/images/wallwthroughwalls/gregminster3.jpg)
Save crystal is not in the palace at daylight:
![Image](http://www.suikosource.com/celes/images/wallwthroughwalls/gregminster4.jpg)
On the balcony:
![Image](http://www.suikosource.com/celes/images/wallwthroughwalls/gregminster5.jpg)
Audience at beginning. No one is in mood to natter:
![Image](http://www.suikosource.com/celes/images/wallwthroughwalls/gregminster6.jpg)
Like the item shop in the Great Forest, this door is just a dummy:
![Image](http://www.suikosource.com/celes/images/wallwthroughwalls/dragonsden.jpg)
Moravia Castle, no treasure behind the mysterious last balcony:
![Image](http://www.suikosource.com/celes/images/wallwthroughwalls/moravia.jpg)
Someone really ensured that you won't re-enter Toran Basement. There is no way back in either:
![Image](http://www.suikosource.com/celes/images/wallwthroughwalls/toran.jpg)