Marburg has no airport so head for Frankfurt/Main, Germany's busiest airport.
By train
By train
Regular services go to Frankfurt and Kassel and from both cities you have extensive connections on the German InterCity train network IC, not ICE.
By car
By car
One of the few German cities not directly connected by the Autobahn, but as you are in Germany there are good alternatives ... From Frankfurt take the Autobahn to GieÃen and than the speed BundesstraÃe 3 to Marburg.