5 hours waiting at Frankfurt airport - what to do?
 

we will be meeting a lady friend in Frankfurt airport to join us for a 20 day trip in Germany.

She will touch down 5 hours earlier than our flight...
..she is a frequent traveller and it is her first trip to Europe.

Instead of letting her to wait for us for 5 hours, and bearing no delay..i'm are considering the following idea to her:

..put luggage in storage at airport or Frankfurt HbF
.. stroll to the Romer square from Hbf and have a cup of coffee... maybe wander around the area...before meeting us at the airport again.

Question is : is it doable in under 4 hours? ..or is there any good idea..

If you won't be flying on from Frankfurt then it's certainly a good plan. It's very easy to get to Romer from the airport - train to Frankfurt Hbf station and then take a tram from in front of the station to Romer or walk 20 minutes.

The train from the airport takes about 10 minutes to the main station and there are trains every 15 minutes. She could have a couple of hours in town before leaving to meet you at the airport.

agreed - plenty of time if there is no onward flight.

If you are traveling onwards by train then perhaps you could meet up at the Hbf.

I actually think it's easier to take the subway (vs tram) to Romer sq. - you connect in the subterranean level from the S-bahn to the U-bahn. I think it's 2-3 stops on the U5 line.

The 3.90 euro S-bahn ticket from the airport will be valid for that further travel on the U-bahn or tram - no need to buy another ticket.

No need to bother with changing from S-Bahn to tram, U-Bahn or whatever. Easiest is stay on the S-Bahn and get off in the very heart of the town at Hauptwache (2 stops after Hauptbahnhof). To Römerberg it's five minutes walk from there.