6 hour layover in Frankfurt - enought time to go into the city?

My experience is that security at Frankfurt takes a while, even if you are doing an airline transfer. I almost missed my connecting flight.

Frankfurt is efficient and fast. In both directions. Once you land, you will be out in the main part of the airport with 30-45 min.

Trains take 11 min. to get into the city from the airport and there is a train every 15 min. Just follow the signs for Regional Trains or S-Bahn. (look for the big green S) This station is under Terminal 1 by Arrival Hall B-1, and the signs will be in English. Just take the escalator downstairs and for Frankfurt, go to track 1. This is where the S-bahns 8 and 9 normally stop. Regional trains may also stop here and your ticket is valid on these too.

Get a group day ticket, called a "Collective Ticket" on the ticket machine (Gruppen karte) which costs 16.40€. This ticket is good for up to 5 people and is valid all day long, getting to and from the airport and on all forms of transportation in Frankfurt. This is the best choice for 2 or more people. These are NOT 24 hour tickets, they are only good for the day of purchase until the trains, etc. stop running for the day, usually around 1 a.m.

The RMV and DB share ticket machines and they are all touch screens. They switch into English and are fairly user friendly. The machines take coins, 5 and 10 euro bills for single tickets and if you are getting a group ticket it will take a 20 euro bill. It will NOT take a 50 euro bill. Change will be in coins.

RMV machines do not take American credit cards for local travel, but the DB does for longer distance tickets.

In Frankfurt you do not need to validate your ticket unlike some other cities in Germany. It is all on the honor system. If you do not have a valid ticket, you will be fined 60 euro immediately.

There is a DB Travel Center located right next to the escalators for the Regional Train Station. They can print your tickets for you (this will cost you 2 euro), take credit cards for payments and give you information about schedules.

If you need to store your luggage at the airport, cost per bag will be 7 € per bag for 3-24 hours. The better deal is to bring your carry-on into the city and store it in the lockers located along track 23 in the main train station. Cost is between 3-5 € and the 5 € lockers are big enough for about 4 carry-ons.

For inter-Europe flights as long as you are going back through security about 1.5 hours before departure, you are fine.

Wow, Ms Jo, Thank you so much for all of the detailed information! You are a wealth of information! Any suggestions on what we should see when going into the city?

Cheryl, it really depends on your interests. When will you be here? There may be a fest happening in the city, or a farmers market. There are several medieval churches, with the Kaiserdom being the most important as the emperors were elected and crowned here. If you are interested in Jewish history, the Jewish Holocaust Remembrance Wall would be at the top of my list of places to visit. The Römerberg is the old town square, and here you can visit the Alte Nikolai church, see city hall (zum Römer), the Book Burning Memorial, and go up on the Eisener Steg bridge for a great view of the Main and the skyline. A visit to the Klein Markt Halle is almost a must unless you are here on a Sunday or holiday.

with the Kaiserdom being the most important as the emperors were elected and crowned here.

A bit too much patriotism. ;) Frankfurt was the place of election, the place of coronation was Aachen, and the place of the first imperial diet was Nürnberg. These provisions had been laid down in chapter 29 of the Golden Bull of Charles IV (1356).

Thanks for the contribution and corrections, Lubitsch.
There were 30 elections and 10 coronations in the Frankfurt Kaiserdom. Over the centuries, there were also coronations in Rome and in Mainz as well as in Aachen. There were elections in Frankfurt even before it became the election city for the emperor, with Frederick Barbarossa being the most famous. He was elected here in 1152, and crowned in Aachen.

Well, from 1562 on the coronations took place in Frankfurt, not in Aachen, probably because it was closer to the Habsburg territory than Aachen, generally more central, bigger and with the infrastructure to provide for all the guests.

Yes, but that was not my point. It was the claim that Franfurt was the place of coronation. To my knowledge, there was never a constitutional act that removed the provisions of the Golden Bull on the place of coronation. Aachen was the legal place of coronation until the end of the Holy Roman Empire, although the coronations were actually held elsewhere. Likewise, from the perspective of canonical law, Rome was always the place of the Holy See although the popes were forced to move to Avignon for a certain time span.

One can also visit the Deutsche Orden Church (Teutonic Order of Knights) which was consecrated in 1309, or head to the neighborhood of Frankfurt Höchst which has one one of the oldest churches in Germany, the Justinus church, consecrated in 850. Höchst is one of the towns on the Half-Timbered Route and has a wonderful Farmers Market from 7-1300, on Tues. Fri. & Sat.
https://de.wikipedia.org/wiki/Deutschordenskirche_(Frankfurt_am_Main)
http://www.justinuskirche.de/files/pdf/leporello/leporello-justinuskirche-en.pdf
http://deutsche-fachwerkstrasse.de/uk/cont.php3?s=10&c=portrait

Ms Jo, thank you so much for your suggestions! You have given us a lot of options. I appreciate your help very much!