I'm going to be in Frankfurt for about a week in late September and I'm looking for things do as day trips from Frankfurt. I'm good with up to about 1-1.5 hour train rides (I'll have a Deutschland ticket, but I'm ok paying for an ICE if need be). I've already seen much of the beautiful part of the Rhein, Heidelberg, Würzburg and Köln on other trips. Marburg and Limburg an der Lahn/Runkel are on the list. I like small towns, photography and I do speak German from my time living in Switzerland. I'm not a museum person, but I am a huge WWII history buff, if that helps to narrow down your suggestions. I'm in my late 50s, fit and tend to travel quickly and efficiently, so just sitting at a cafe isn't my thing (but I'm not opposed to a good Biergarten or Heuriger!).
My favorite towns to visit using regional trains, all within one hour of Frankfurt: Büdingen, Gelnhausen, Idstein, Seligenstadt, Mainz, Bad Homburg (include the Saalburg Roman Fort and Hessen Park Open Air Museum), Kronberg, Königstein, Eppstein.
@Ms Jo Thanks so much for the reply. Originally I was thinking Idstein, but after a bit of research, it almost looks a bit Disneylandish/very touristy to me. Just a cute square, a tower, church and remains of a castle - like a mini Rüdesheim or St. Goar. My guess is that you could see everything in a few hours. Am I missing something?
Well, Idstein is more authentic as the houses are all original. The Klinger Haus is amazing. Rüdesheim is the most touristy town of all, with almost all of it rebuilt. St. Goar doesn't really have a lot of half-timbered houses, but does have a great church.
Idstein has the Hexen Turm and one of my favorite churches, the Union church. But, yes, you can see it all in a couple of hours. Maybe combine it with a visit to Eppstein since they are on the same S-bahn line. The castle there is a ruin, but still interesting to walk around and see the museum inside. If you do go to Büdingen, book a private tour that takes you inside the massive stone walls and up on the towers. If you go to Gelnhausen, go to the Barbarossa palace ruins. They are pretty impressive.
I like small towns, photography...
It's the strangest thing... rarely does anyone here mention the Bergstraße towns which line up neatly on the railway between Frankfurt and Heidelberg. The Regionalbahn trains stop at every little half-timbered wine hamlet with a station, completing the run in Heidelberg after 90 minutes. So you could easily visit a handful of these towns throughout the course of the day and return to Frankfurt in the evening.
https://diebergstrasse.de/wp-content/uploads/2025/04/Holiday-Route-2024.pdf
I stayed 3 nights in Limburg a few years ago. I really liked it.
I hope to get to Idstein this year
If you want to branch out from WWII, I concur with Ms. Jo that Bad Homburg and the Saalburg Roman Fort are a great way to spend the better part of the day.