I had this question again recently and it’s pretty common in any discussion group for Frankfurt. A byproduct of having a big transit airport! So if you have a layover at Frankfurt airport and you are considering whether you have enough time to get into the city and see anything of interest, here’s what you need to know:
How much time do you need?
The ride to Frankfurt main station is 13 minutes and the trains are regular. You will normally not have to wait for more than 20 minutes for a train, but normally a lot quicker. The station is underground at Terminal 1, so if you are coming from T2, add 20 minutes transfer as well to be safe. When you exit T1 security, walk straight on towards the terminal building exit. Before going outside there will be escalators down with signs for Bahnhof/Trains. Head to platform 1 but buy a day ticket at the machine before you go on to the platform. In total about 10 minutes of walking inside the terminal before you are waiting for the train.
So best case scenario, you will need 30-45 minutes to get from security into the city centre, depending on how good at reading signposts you are!
Where should you go?
If you are on a limited time visit, you want to spend as little time as possible on a train. Luckily Frankfurt is a small and very walkable city, but you still need to get off at the right stop. Best place to head for is Frankfurt Hauptwache, which is two stops after the main station (Hauptbahnhof). Make sure you get on either the S8 or S9 from platform 1 at the airport, the Regional (RE2) train only goes as far as the main station and you’ll need to change or enjoy a less than picturesque walk through the Bahnhofsviertal.
Arriving in Hauptwache brings you right into the centre of the shopping and food district, and a few minutes walk from some of the top sights worth seeing.
What to see?
Best part about this list is that you can do all of these four key ideas on foot and with about 5 minutes walk between each. Afterwards you can hop straight back on to the S-Bahn 8/9 at either Hauptwache or Konstablerwache for a direct ride back to the airport. I would recommend 3-4 hours at least to cover everything comfortably, but you can also do the whole thing in 30 minutes if you just keep walking!
Römerplatz and the Altstadt
The old city square surrounded by classic buildings, including the Townhall, restaurants, cafes, souvenir shops, and even some where selling year-round Glühwein. Depending when you come, it could be completely packed, especially if there is a festival on. From Römerplatz you can then wander through the newly finished streets of the new ‘old city’ (neu Altstadt) in the direction of the cathedral.
Eisener Steg
This old iron footbridge across the river Main is just a couple of minutes walk south from the Römerplatz and is the best place in Frankfurt to get a selfie with the view of the city behind. It is also the place to go if you also want to add a padlock to a bridge and throw away the key! The light is best in the evening when the sun sets behind the city skyline
Dom/Cathedral and its Gothic tower
Shown in the bottom right hand corner of the image, you can see what an amazing view over the city you are going to get. Dating back to AD 852, the cathedral is stunning in its own right, but climb up the 66m, 300 step, Gothic tower for an amazing view of the city.
Kleinmarkthalle indoor market
Not the best photo admittedly, but inside is packed full of small traders, restaurants, cafes, tapas, bars, and souvenir opportunities. So tightly packed, its impossible to get a nice photo of everything indoors! Perfect place for local or international food and a drink before you head back to the airport.
Note: timing is important! The best time for views is around sunset, however the Cathedral closes its doors at 6pm everyday (closed on Mondays though) and the indoor market shuts every weekday at 6pm and 4pm on a Saturday (closed on Sundays).
Enjoy your visit!
Living in Frankfurt 
Great article! There are so many people who have layovers or begin/end their trip in Frankfurt so we shared this in our FB Group “Traveling and Exploring in Retirement (Traveling Expats).”