Römerberg in Frankfurt 

The Römerberg is the city center of Frankfurt. Named after the city hall - Zum Römer, it is a beautiful plaza where the Christmas market is centered each year as well as other festivals. It is bordered by the Alte Nikolai church built in 1290, and reconstructed half-timbered houses, the Paulskirche, as well as the Frankfurt Historic Museum, adjacent to the new Alt Stadt, Franconoford, and watched over by the Kaiserdom.
Easy to reach by U-4 or U-5, Dom/Römer stop, a 5-minute walk from the Hauptwache where the U-6, U-7, and all of the S-Bahns stop, or by trams #11, 12, or 14 at the Römer/Paulskirche stop.