DB timetable
http://reiseauskunft.bahn.de/english.html
From: FRA (for Frankfurt Airport)
To: HD (for Heidelberg Hbf = Hauptbahnhof = main railway station)
and
From: HD
To: Buxelles-Midi (this is the main railway station in Brussels)
As you wrote "we" - don't forget to increase the number of travellers at the
DB timetable to get the correct prices.
Frankfurt Airport - Heidelberg: buy a single ticket when you arrive at
Frankfurt Airport
Heidelberg - Brussels: buy this ticket in Frankfurt or Heidelberg - here a
seat reservation might be useful (compulsory if you use a Thalys train from
Cologne to Brussels).
A normal return ticket costs 2 times of a normal single ticket. Only if you
buy in advance and for fixed trains you can get a discounted ticket - if
available (restricted in numbers). For Frankfurt Airport to Heidelberg and
back this makes definitly no sense.
Here a tip to save some money:
Add at the DB timetable "Koblenz" as a "Via" station for Heidelberg -
Brussels. Thus you'll get slower (~ + 1 hour) but also cheaper (~ EUR 20-25
for 2 persons) connections through the Middle Rhine Valley
http://www.talderloreley.de/index.en.php
If you have still some time left, you could interrupt your journey in Colgne
for 2-3 hours and visit e.g. the cathedral (Germany's most visited building;
UNESCO world heritage; was even once the highest building on the planet).
The fastest route from Frankfurt Airport to Heidelberg is via Mannheim Hbf.
No need to travel to Frankfurt Hbf.
There are direct IC trains from Heidelberg to Cologne through the Rhine
valley. These trains go actually neither through Frankfurt Airport or
Frankfurt Hbf, but via Mainz Hbf.
Best is just to follow the route advices of the DB timetable.
Basically there are 3 parallel major railway lines running 5-15 kms from
each other here in South-North direction.
(this attempt of an outline will be only correct with fixed size font like
Courier)
Mainz Hbf --- Frankfurt Airport --- Frankfurt Hbf
| | |
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Ludwigshafen Hbf --- Mannheim Hbf --- Heidelberg Hbf