Dear Twilight,
I thank you for your vested interest in refurbishing the old castle so soon after your previous excavation there. I didn't think you'd readily accept my request, much less enlist your friends to help, so please extend my thanks to them as well.
You don't know how much this refurbishment will mean to us. It's the last step in helping us bury the hatchet we wielded so long ago, back in a time where our fights were more heated, and our friendship was strained to a breaking point over petty squabbles like who ate the last sugar cookie. Now that we've recovered that friendship, seeing the old castle look new again--or what remains of it, at least--will finally close a millenium-old wound.
But if I might make a suggestion, since you obviously know about all the trap doors and secret passageways, I'd like you to keep those the same. You may modernize the other parts of the castle at your leisure, but keep those hidden hallways the way they are.
I won't go into great detail why, but Luna and I have hidden some things in there that... aren't for your eyes to see, nor your friends. No, it's not another great evil or powerful artifact that shouldn't fall into the wrong hooves or anything exceptionally dangerous. At the same time, they shouldn't see the light of day for... reasons. In other words, some secrets are meant to stay that way, so don't go looking for them during the refurbishment.
In fact, just try to stay out of those hallways completely. I don't want you kicking around loose stones or tapping the walls for hollow sounds, or even stepping on weighted stones that may or may not suddenly open said hollow areas. Don't. Do. It. Just stick to cleaning and touch-up, and everything should be fine.
But if you do stumble across such a room somehow, well, stay out. That's it. Don't enter the room, or even so much as poke your head in. Touch absolutely nothing in those rooms, nor take anything from them if you somehow ignore that last statement. I mean it! Leave everything in there alone, especially the books! They're... not ordinary books, okay?!
Sincerely--seriously, stay out,
Princess Celestia
Yes, I warned her, Luna. Our secret comic book stashes ought to be safe.
Well, they shouldn't have rotted. I vacuum-sealed mine in plastic, and so did you, right?
Uh, no, that sort of protection ward fades after a century without maintenance. I'm sorry, Luna.
Well, I suppose if they haven't found them yet, I can share mine with you. Don't worry--I trust you'll read them without stuffing your face with moon cakes while reading them.
Yes, I'll also take a look and see if they're still sold on the market. Anyway, while we wait for them to finish, let's get started on those pies, okay?