If money and location were of no concern, I would without a doubt get married at the Boston Public Library.
Das Beethovenhaus in Bonn
The Christkindlesmarkt in Nürnberg
Schloss Schönbrunn in Vienna
Chamonix in France
Enschede in the Netherlands, aka the farthest my Deutsche Bahn card took me
The Catacombs of San Callisto on the Via Appia Antica, Rome
My motto :)