"Every major city has an Underside. The older the city, the larger the Underside. I don't know about Luxor - I'm not certain if Undersides continue to exist once the cities they existed beneath cease. It's something to think about."

And it is, actually. It makes Tom want to travel, to delve, to find out what's there under the sands and ruins of ancient places. There must be magic and knowledge undreamed of.

In this way, Tom's not changed. Voldemort is a very curious monster.

"I think he's more focused on the Topside right now, though. Perhaps you ought to owl Dumbledore. Let him know what you've found."