Is such a day-trip by rail doable?

It takes about 2 hours, 20 minutes each way, and the train stations are right in the city. So I guess it's theoretically possible, although it wouldn't be my choice.

And it may not be mine, but there is a beautiful cathedral a short walk from the station.

Why not?

The direct ICE train takes 2:38. The train is very comfortable and has a restaurant car which offers decent food and drinks.

Get up early in the morning, proceed directly to the train station and have breakfast on the train. Relax in your seat and take a nap. Read a good book. Listen to music. Chat with your travel companion. It is a very relaxed way of travelling.

The connection is direct, and once you are in Köln main station, it is a few steps to the cathedral.

When you take the 8:04 train you will be in Köln at 10:45. To return, you can either take the 17:48 arriving in Amsterdam 20:25 or the 19:17, arriving at 21:55. Again, take dinner on the train. Both options give you plenty of time Köln.

You can visit:
- The cathedral.
- The Roman-Germanic Museum - on of the best museums of Roman culture at all.
- The Wallraf-Richartz-Museum - a world-class museum of historical art.
- The Museum Ludwig - an excellent museum of contemporary art.
- Groß Sankt Martin - a romanesqe church.
- The riverfront with a little park and cozy restaurants.

All these attractions are a few steps from the main station.

A few hundred meters away is the City Hall with remnants of the Roman palace underneath and with a 200-meter-section of a Roman sewer, walkable.

A little further you find the chocolate museum.

So many options...

jmf, I did this daytrip last April and it was really easy. I did basically what traveller says, taking an early train and eating breakfast on it, and a late train back.

We spent most of our time in the museums, especially The Wallraf-Richartz-Museum and the Museum Ludwig, but the cathedral is stunning. There is a lot of window (or actual) shopping to be done nearby the cathedral. We ate near the cathedral at Fruh (I think that is what it was) and then headed back to Amsterdam. It was a nice day away.

I was there about a decade ago. I found a beautiful Czech crystal necklace at a jewelry store just a short walk from the cathedral. My wife loved it and was broken hearted when it broke some years later. I'd love to get her another one.

But I must admit that the transit time seems more than a bit excessive ...

It is over 260 km to Cologne from Amsterdam, and it is actually quicker to take the train than to drive it, and certainly more relaxing!

Should we choose to do this, would our Holland Rail Pass get us a discount?

The Holland rail pass would pay for the journey in the Netherlands, so you'd need to buy a ticket to cover the fare from the Dutch border to Köln, plus probably a supplement for the ICE train.

You can buy 19-Euro one-way tickets in advance on Bahn.de, so I wonder if you would save money with the pass once you paid those extra amounts that GeoffHamer mentioned.

I've looked at tomorrow and at a date in one or two months' time, and the ICE fare from Amsterdam to Köln shows as 55.60 euros. The 19 euro tickets seem elusive. If you can find a 19 euro fare and don't mind losing flexibility, then it's probably the cheapest way.

That's true, as I bought our 19-Euro tickets three months in advance.