"Is this some kind of illusion magic?"

"Oh, that's right, muggles see the castle as a ruin--we definitely need to find you a teacher, they'll be able to counter it for you. Just follow us for now."

"That would be dicey if I were afraid of heights but fortunately I am not. Why does it look like a ruin in particular?" Follow follow.

"Something people won't want to investigate as much as a castle, I think."

"What exactly did you mean by 'indestructible'?"

"I can get papercuts. If you attack me with a sword, it'll look sorta like I got a papercut. And either way it'll take a second or two to heal unless for some reason I want a papercut. Extrapolates as you'd expect given that."

"That's amazing."

"Well, hello children! And who is this?"

Very quiet "augghh".

"...uh, hello, I'm Cam, and you?"

"Why, don't you know? I'm Gilderoy Lockhart! Order of Merlin, Third Class, banisher of the Bandon Banshee, and five times winner of Witch Weekly's Most Charming Smile Award. Also Hogwarts Defense Against the Dark Arts Professor. Excellent wings, by the way, very imposing."

"Thanks, I made them myself."

"Professor, could you get him one of the charms that let Muggles see Hogwarts?" 

"Certainly, Miss Granger, anything for my most attentive student. Right this way." He sweeps off with a swirl of robes that's a bit too dramatic to not look rehearsed.

Okay, they're following this guy then. It remains a really good thing Cam's not afraid of heights. "This requires going somewhere? Do you not have your wand on you or do some things require extra doodads?"

"It's a necklace. A lot of persistent magic is enchanted objects; it's less likely to come undone that way."

"You should be glad it's a necklace," Harry mutters too low for Lockhart to notice. "Last time he cast a spell on me he got it wrong and I spent the night in the hospital wing."

"Huh. And there's just one around? Who-all comes to visit under typical circumstances?"

"I think all the teachers have a couple? It's mostly people's muggle parents."

"How considerate of them to have this, uh, disability accommodation on hand."

"Guess so, yeah. I haven't really thought about it, all my family are magic."

"I would be interested in pie charts of the demographics here but it is not urgent."

"You make charts out of pie?"

"It's a figure of speech, the charts are circles with wedges of different colors."

"That makes more sense but it's not as much fun."