Long layover!

You are in Germany, drink beer!

Ride the S-bahn into the city. It only costs 3.90 € one way, and only takes 11 minutes. You can catch this train at the Regional Train station in Terminal 1. The escalator is right by Arrival Hall B-1. Go to track 1, buy your ticket from the easy to use touch screen machines and get on any train coming by, as all the trains from track 1, go to the city, and the Hauptbahnhof. The machine will not take credit cards, nor large bills. Walk along the river, visit the Kaiserdom and the Römer. You could go to the Jewish Holocaust Memorial Wall, go to the Karmeliter Cloister with the largest religous wall paintings N. of the Alps. Stroll through the Klein Markt Halle or take a walk past the Alte Oper or the Eschenheimer Turm. If you like visiting old churches, go to the Alte Nikolai on the Römer, built in 1290, or the Deutsche Orden church, built in 1309. The museums are usually closed on Mondays, so with any extra time you have, have a seat at any of the 100's of cafes that line the city streets and have some good German food. My recommendation is one of the applewine gardens in Sachsenhausen. My personal favorite is Dauth Schneiders.

The Old Town area is interesting, and adjacent is a very large pedestrian shopping area. good to stretch your legs. There is also a Ratskeller at old town (always one of my favorite places to eat in Germany0. Tons of walking in that area (see Jo's suggestions above0

Follow Jo's advice. Take advantage of the fact that your layover happens to be in one of the most accessible airports from town.

We had a long layover in Frankfurt and it was so fast and easy to get into the city, have lunch and walk around. We never felt rushed at all. It was a great way to stretch our legs in between long flight journeys.

If you can afford a car rental, you can get out to the Rhine River and tour a few castles. Go to the area around Bacharach and St. Goar. It's beautiful and so close by.

'If you can afford a car rental, you can get out to the Rhine River' Even if money's not a factor, time is. Assuming it takes a half hour to rent a car, another half to turn it in, and you need to be back at the airport only two hours prior to departure - - that three hours shot. Boppard is two hours away if you know exactly what you're doing (and the road into the gorge at Bingen is torn up with construction, so you have to braile your way into the gorge). That's four more hours down the tubes, leaving only two to look at stuff. Listen to Jo.

It only takes 1 hr to 1h20m to get from the airport to Bacharach by train, €10,50 for the RMV ticket. Or, 1h13m to 1h32m to St. Goar, €15,80 one way. Actually, for St. Goar, €3,90 one way (€7,80 RT) to Mainz, and €21 for a Rheinland-Pfalz-Ticket, €28,80 would be less and give you HOHO travel anywhere in the Rhein valley.

Thanks all! I am very greatful to you all!!