Seeing Europe

You could copy this itinerary but do it yourself.
https://www.ricksteves.com/tours/europe/europe-21-days
I never have used a guide (only for hard to reach places on day trips) but always consult guide books
Forget passes (except for Switzerland) and forget Euro rail.
Buying point to point tickets using the train is the best way to travel.
You can get one of those Europe Guidebooks to get an idea on where to stay or look on trip advisor.
The guidebooks help you figure out geography as they have maps
But you should pinpoint where exactly you want to go in order first. Then post your itinerary and someone here will edit it

How to visit Europe independently without a guide if you only have one chance independently without a guide? I would like to visit for 3 weeks from DC and visit as many cities as possible

1. You don't need a guide.
2. You don't have "only one chance" - and telling yourself that you do is a tremendous mistake because it inevitably leads you to making disastrous choices, which will ruin your trip. For example, here's a big one:
3. "I would like to visit for 3 weeks from DC and visit as many cities as possible." (followed by a list of 22 places, a mix of country names, regions and cities). That is a guaranteed recipe for a hellish deathmarch trip, which leaves you heart-broken and full of regret (because you won't see a damn thing, because you will spend all your time zigzagging between places and never actually being anyplace).

If you have 3 weeks, cut your list down to a much, much shorter wish-list (maybe 10-ish - remember, less is more). You need to prioritize, and save whole swaths of the continent for future trips. You can't see all of Europe (or even half the places on your initial list) in 3 weeks. Think of it this way: if you wanted to see all of North America in 3 weeks, going everyplace from Alaska to Mexico to Florida to California to Maine...even if you just wanted to just spend a day or two in each place (imagine trying to "see" California in 2 days? Alaska? Mexico?). It simply can't be done and it would be a big mistake to try (because you can't and won't). Instead, focus on a region or a few regions (say, the US west coast and New England, plus Florida...that could make a nice, though still very busy, trip....so do the same thing for Europe...pick a maximum or 2 or 3 regions, eg Spain and Italy plus a few days in Paris....that's still a lot for 3 weeks, probably too much, but it'll get you at least in a rational starting place...you could spend 3 weeks in any of those places and not run out of good stuff).

As a starting point, take a look at some of the "suggested itineraries" and the longer tours offered by Rick Steves (start here: All Tours) - but (important!) don't think that you can maintain the pace of an organized tour! As a first-time traveler you will not be very efficient with your time. You will get lost (often). You will struggle to understand countless things (that can actually be quite enjoyable, but it wastes time). You will need to burn time finding your way and due to a hundred other reasons (on a tour, all the work is done for you).

From a practical standpoint, with the still-unfolding twin disasters of the worldwide pandemic and the economic fallout to follow, nobody is going to be flying off to Europe for a trip anytime soon. It could easily be a year (or two or more) before we can even dream of resuming the kind of travel that we have enjoyed up until a few weeks ago. You have plenty of time to plan your trip. Don't be daunted by the task, planning is fun and not difficult (and it's all we can do now). Good luck.

What you are proposing is impossible. I don't mean to rain on your parade and I am being blunt. You need a hard dose of reality. Even if you had year it might work but three weeks is out of the question. Get a map, put some pins in it so you understand or recognize the distances involved. With three weeks (20 nights) on a rapid schedule you might be able to visit a max of six cities if you stayed in a general area.

We have spent nearly a year total in Europe over the past twenty plus years and could only tick off about half of your list. It is not workable. You need to come back with a prioritized list of the three or four counties/cities and maybe we help you put together trip but till then it is a waste of our time.

Slow down, study a map of Europe, eliminate nearly 2/3’s of where you want to go and read a couple of guidebooks in order to understand you cannot possibly do that itinerary in 3 weeks.

Agree with all above, slow down, move less and enjoy more :)

With only three weeks (21 days), I would strongly suggest you limit yourself to three countries at the maximum! With Ancient and Christian History, as your main driving forces, I would recommend you stick with countries in which the layers of 1000s of years of history are abundantly on display and easily accessible.

My top choices would be:
Greece/Aegean (Athens + an Island + Kuşadası in Turkey)
Italy (Rome + Naples)
Spain (Andalucia)

I'd recommend seeing the above in mid-late Spring^

Thank you Carlos. This is what I was looking for.

Happy to help :)

Kuşadası in Turkey, has Ancient Greek, Roman, Venetian/Byzantine, Ottoman, and Christian (includ. house of the Virgin Mary) sites all within a relatively short distance, a good "bang for your buck" + the local cuisine is most excellent!

Carlos - Can one ferry to Kuşadası Turkey from Greece ? if so from which Greek island, or is flying the only option?

Hi RJean, there are daily ferry services to and from the nearby Greek island of Samos. Kuşadası is also a popular stop for eastern Mediterranean cruses.

Ah wonderful! So i would fly to Samos from Athens and take a ferry to kusadasi. You got me inspired to go there once we are over this crisis. I love exploring archaeological sites. I will enjoy exploring Ephesus.

Thanks Carlos!

And if you go to Ephesus, continue a short distance north to ancient Pergamon as well.

Hi! I love your wish list but you have to be more realistic and if you want to have a good time and actually stop,relax and enjoy the places you want to visit, you have to cut your list in half.

What I suggest is first going to the Balkan Peninsula and Turkey. That includes Croatia, Montenegro, Macedonia, Greece and of course Turkey.

The cities you want to visit in those countries are Dubrovnik, Split, Corcula in Croatia... Kotor in Montenegro, Skopje ( the Mother Theresa museum) and Ohrid in Macedonia, Athens, some of the islands (Rhodes, Corfu,Crete) and Kusadasi for Ephesus, Cappadocia and Istanbul in Turkey.

If you have more time left on your hand, Italy is the next country you want to visit, Rome, Mila, Capri island, Amalfi coast..... Naples for Pompeii...

I suggest you take another trip to Europe to visit western Europe including Amsterdam, Paris, Copenhagen, Berlin, Dublin, London....

I know it sucks..but hope this helps! Have fun