Board Thread:Spoilers!/@comment-26261400-20150826194347/@comment-25926288-20151019220435

MasterofCows wrote: Did the sand of Avalon make the castle appear, or just make it seem like it appeared? For better or worse, the castle appeared because otherwise, everyone would have fallen an walked through fake doors, lol. It created the castle to "fix" the broken kingdom. So, it actually created it, but the kingdom being the way it is is an illusion.

In simple terms, the castle is just a magic structure, like Storybrooke. Or with a cloaking spell. When SB had a cloaking spell people passed right through the road and never found Storybrooke.