Koldawne
W:O:A Metalhead
Well, just a small advice, if I were you, I'd see if you can book your ICE/Thalys trains from Cologne to Brussels now. It's cheaper than when you have to buy them just before you go.
ICE: www.bahn.com (in English)
Thalys: www.thalys.com (In French/English (and more))
Edit: The cathedral in Cologne is probably the Dom. It's right next to the Hauptbahnhof. Main exit, can't miss it.
I don't know about the Aachen cathedral though.
yep I think that was it.. "the Dom" I remember it is right next to the Hbf. We have rail passes and yes we do all the reservations before hand. I wouldn't want to have to miss a train because it is full. I almost did that last time because I had left one too late and had to pay full fare for it