It contains relics of the Three Wise Men, and its ladychapel has a triptych of the adoration of the Magi done in the 1440s by the town's most famous painter, Stefan Lochner.  It was built on the site of a Roman villa, some of whose mosaics can be found next door in the Roman-German museum.  Although begun in the 13th Century, work on it stopped in 
It contains relics of the Three Wise Men, and its ladychapel has a triptych of the adoration of the Magi done in the 1440s by the town's most famous painter, Stefan Lochner.  It was built on the site of a Roman villa, some of whose mosaics can be found next door in the Roman-German museum.  Although begun in the 13th Century, work on it stopped in 1560 not to be resumed until 1842.  FTP, name this cathedral located in and named for a German city on the Rhine.
It contains relics of the Three Wise Men, and its ladychapel has a triptych of the adoration of the Magi done in the 1440s by the town's most famous painter, Stefan Lochner.  
Cologne Cathedral or Koln Cathedral or Kolner Dom