I have a US passport travelling to Austria then want to take a train from Vienna to Athen, Greece in September 2023. The train passes through Serbia and Macedonia which are not EU or Shengen. Will I be able to take this train, through Serbia, and Macedonia without a visa? or without other issues? Is this recommended or is there a better, preferred way to get from Austria to southern Greece? Thank you! New traveler

You should check the US Embassy website for any visa requirements for Serbia and North Macedonia (note the name change). But, and don't quote me on this, as US traveler, there likely is not a visa requirement for either country. I have been to Serbia, but not North Macedonia.

Now, this is a very long train ride. Any reason? I do not advocate flying often, but between Vienna and Athens, flying would overall be quicker and perhaps even cheaper.

Edit; because these countries are not Schengen, one thing you might have to be aware of is border crosdings. There very likely might mean you have to pass through passport control - perhaps even asking the train to depart in this process. I am not sure that this is a definite (I have not done train in this region) but have traveled by bus throughout. You may consider asking this to "locals" on Trip Advisor for more specifics.

Because of this, if you are only traveling between Athens and Vienna with no other plans to stop, I'd just fly.

No specific reason for train. Will look into the cost of flying! Thank you!

You're welcome. Also note that I had edited my post about possible border considerations that might also help with your decision.

https://www.seat61.com/international...#Vienna-Athens

three options, one suspended

If I read it correctly, it only shows two options with one being suspended -- meaning one option. And that one takes 3 full days

First of all: a direct train ride from Vienna to Athens is not possible.
You could choose between:
Vienna - sleeping car - Bucuresti - bus Giurgiu - taxi - Ruse - train - Kulata - taxi - Sidirokastro - bus - Thessaloniki - train - Athens;
Vienna - sleeping car - Ancona - overnight ferry - Patras - bus - Athens.
Flights are usually faster and cheaper.
If you want to go to Southern Greece, you may book a direct flight from Austria, Budapest or Italy to Chania, Heraklion, Santorini, Karpathos or Rhodos.

Check the Aegean Airlines website. I'm seeing airfare as low as €89 depending on the day.

Isn't the route through Thessaloniki still closed after the terrible crash earlier this year? Which is why Seat 61 says it is not available.

I guess it depends on how urgently you need to get to Athens whether the trip through Italy and the ferry appeals. A bit of slow travel making the journey part of the experience as opposed to yet another crowded flight and airport hassles. Obviously if you have to be in Athens the same day you leave Vienna then a flight is the way to go.

There are no somewhat direct trains between Beograd and the Greek/Macedonian border at Idomeni and no trains at all from there to Thessaloniki.
IC trains beteween Thessaloniki and Athens run again since months.

To begin with, there isn't a direct train route from Vienna to Athens available. Your options include:

1. Taking a train from Vienna to Bucuresti with a sleeping car, then transferring to a bus to Giurgiu, followed by a taxi ride to Ruse. From there, you can catch a train to Kulata, another taxi to Sidirokastro, and finally a bus to Thessaloniki before taking a train to Athens.
   
2. Alternatively, you can board a sleeping car train from Vienna to Ancona and then embark on an overnight ferry journey to Patras. From Patras, you can take a bus to Athens.
   

However, it's worth noting that flights are typically both faster and more affordable. If your destination is Southern Greece, you might consider booking a direct flight from Austria, Budapest, or Italy to Chania, Heraklion, Santorini, Karpathos, or Rhodes for a more convenient travel experience.

There has been a temporary NightJet train between Vienna and Ancona, but this will end in 2 days. I've just returned from Vienna with this train.

​​​​There are now only day trains, which take at least 12 hours, with two changes of train. You probably would need to spend the night in Ancona.

I supposed the OP has already booked his trip.
Despite the suppression of the Vienna - Ancona overnight train, it's perfectly possible to reach Athens by sleeping car, overnight ferry and bus:
Vienna dp 19.18 - sleeping car - Florence ar 7.00, dp 8.14 - Frecciarossa - Bari ar 14.10, dp 19.30 - Patra ar 13.00. Bus Patra - Athens (3 hrs journey) every hr.