Central base of operations for touring European Cities

Brussels or Paris is a center. You probably are better off going from country to country. Italy of the ones you mention is out of the way.
Get the Rick Steve's Europe Book which has suggested multi-country trips mapped out.

Or look at some of his best of Europe tours to get an ideas that you can do yourself
https://www.ricksteves.com/tours/europe

Without being a little more specific about what you are hoping to see, not sure how helpful people can be.

Better yet - Get a map. Put pins in the map and draw 150 km circles around the cities. Europe is fairly good size and not everything is within a day's trip. Depending on what you want to do or see, it would be series of many cities. And how time do you have? The most you want to do in a day would be about 150 km, 100 miles or a bit more if a fast train is available.

If you restrict yourself to one country base, that means you'll see that base city plus anything within 2-3 hours train ride each way (I assume you won't want to be in transit more than 4-6 hours per day?). The base is really dictated by your interests in the base city and the day trips that are feasible from that base city (in other words, you won't be able to see many places in Italy is you base yourself in Florence, but you'll easily see the towns that are close by). Each of these countries is very large and distances are far within and between them. I would look at a good Europewide book (Rick Steves and other have one) to string together a logical itinerary. I probably wouldn't focus on more than one country per trip unless you're seeing places that are close to the border with the adjacent country.

The capital cities will have the best transport links.

Sorry, but your question is far to vague for anybody to provide any meaningful advice. What are your interests?

What on earth is a base of operations?

How long is your trip? Hopefully at least 8 weeks to cover these 4 large countries plus your cruise.

Gotta disagree with Jennifer. I think your question is broad but clear, and I think Frank's suggestion of a 150 km travel radius is meaningful advice.

I often use a travel-base strategy for visiting a region. It works well if you pick the right bases. Sometimes those bases are major, major cities, sometimes not - it depends a lot on the region.

Rick Steves guidebooks are alright but not necessarily the answer to your question since your stay will always be a good transport hub - that is not his particular travel style or focus.

I'll make a couple of suggestions for Germany, which I know better than the other places. I'll list day passes for round-trip train outings - buy all of them at the station on the day of travel from a ticket machine.

1. NUREMBERG is an interesting city and a really productive railway hub.

VGN Tagesticket Plus regional day pass for two = €19.10 - use it to travel to:

Bamberg (45 min.) - http://whc.unesco.org/en/list/624
Rothenburg (75 min.) - https://upload.wikimedia.org/wikipedia/commons/7/71/Rothenburg_BW_4.JPG
Bad Windsheim (55 min.) - https://www.tripadvisor.com/Attraction_Review-g198421-d284746-Reviews-Frankish_Open_Land_Museum_Fraenkisches_Freilandmuseum-Bad_Windsheim_Middle_Francon.html
Bayreuth (55 min.)

Bavaria Ticket regional day pass for two = €31 - use it to travel to:
Würzburg (70 min.) - http://www.wuerzburg.de/en/visitors/must-sees/index.html
Regensburg (60 min.) - http://whc.unesco.org/en/list/1155
Munich (115 min.)

2. MAINZ is an attractive university town on the Rhine River 25 minutes by train from Frankfurt Airport. It has a large pedestrians-only zone, lots of museums and fine churches, and a nice old-town quarter, as well as a great position for train outings.

Use the Rheinland-Pfalz ticket day pass (€29/2) for train outings to...

Bingen (20-30 min.), the gateway to the scenic and historic Rhine River Valley and the best starting point for a river cruise through castle-country to St. Goar, home of Rheinfels Castle. The R-P day pass gets you by train to Bingen and also back to Mainz from St. Goar. Stop in old-world Oberwesel and/pr Bacharach on the way back.

Worms (25 min.)

Braubach (95 min.) home of Marksburg Castle, the only never-destroyed medieval Rhine castle - take a tour.

Use the RMV day ticket, €28.30 to...

Frankfurt (40 min.)

Use the RMV day ticket, €16.40 to...

Rüdesheim (45 min.), across the river from Bingen... wine town with numerous tourist attractions. (Can be combined with Braubach and Marksburg Castle using a R-P day pass instead.)

The best French city for this strategy is Paris, the hub of the rail system.

Personally this idea has never appealed to me, because it is so limiting and entails so much time sitting on trains. But at one point there was a whole book about it.

Hi,

If you choose to use a city as a "base of operations," how about Strasbourg, ie direct TGV connection to Paris, connect to Berlin with only one change of trains, likewise with Frankfurt. For traveling in Europe, I don't use the "base" concept, not my style, not worth it.

What you describe can be a recipe for many wasted hours in transit. If it's more than 90 minutes away from your base then forget it as a day trip option. That's 3 hours of your day gone. Pack smart (light), stay near the station, be prepared to move on.

I am not a big fan of staying in one place as a base for day trips, because the places that lend themselves to being a base are big cities where you pay top dollar (Euro) for a hotel. You might spend half and hour to 45 minutes just getting to the train or bus station, depending upon your hotel, plus travel time to your day trip destination. But since you asked... Italy: Florence is well connected to many good day trips. Lucca, Siena, Fiesole, and others. Rome at least a few (Ostia Antica, Orvieto). Germany: Nuremburg is well connected by train to many places (Bamberg, Munich, etc). The train station in Nuremburg is right near a nice area in which to stay as well. A day trip strategy can be a steal within Bavaria because of the Landes tickets, 25 Euros or so for two all day travel on regional trains. In England you could either choose London ($), from which all transit connection radiate, or head to the southeast. London is one where the hotels are especially expensive, and some of your day trips options might leave from a far away train station that takes an hour to get to on the tube. The area around Dover/Canterbury/Rye/Brighton is pretty well connected by train (and probably bus). In France obviously Paris offers lots of day trips (Giverny, Reims, Chartres, Versaiiles), but the logistics might not be that easy and it could get very expensive. i.e. the train to Chartres might be the other side of the city from the train to Reims. In Germany Dresden might be worth looking into as well. Saxon Switerland National Park, Goerlitz, Prague, Berlin might be within range. One of the best cities for day trips, in a country that you do not mention, is Madrid. El Escorial, Segovia, Toledo are all reached easily and cheaply by bus and/or train. Lisbon also has some good ones: Sintra, Cascais, and more. Eger is a good day trip from Budapest. Budapest itself is easily worth three to four full days. I suggest that you look into the logistics using local transit websites, or bahn.de as a fall back, and choose accordingly.

Because of its incredible wealth of great sights, and their close proximity to one another, Italy does lend itself to such exploration.

From Milan
Visit Bergamo, Pavia, Lake Como

From Vicenza
Visit Verona, Padova, Lake Garda

From Bologna
Visit Ferrara, Ravenna, Parma, Modena

From Florence
Visit Lucca, Pisa, Siena, Chianti

From Sorrento
Visit Capri, Positano, Pompeii, Naples

to vague and not a reliable principle anyway. The most convenient city in England from where you could cover a huge proportion of the country in day trips would be Birmingham - and the central area isn't really a tourists dream!

There are a couple of ways to do it. If you want one base city and day-trip or over-night into other cities also consider Cologne.

It's a low-cost air hub with cheap and easy air access to pretty much every major European city.

It's a rail hub to the Rhineland area, the Moselle river area, only 2 hours from Amsterdam or Brussels and under 4 hours by train to Paris.

It's a bohemian city with modern but traditional local nightlife, it's got the world's largest Gothic cathedral and - if needed - is a shoppers' paradise.

Cologne and nearby Düsseldorf are easily accessible from the States - and Frankfurt Airport, too, is only about 90 minutes by train.

If you restrict yourself to one country base, that means you'll see that base city plus anything within 2-3 hours train ride, or a 1-1.5 hour plane trip each way (I assume you won't want to be in transit more than 4-6 hours per day?)

2 or 3 hubs in a 3 to 4 week period I suspect will give you a better view of Europe. Look for cities with great train and discount air carrier connections. Maybe Milan, Berlin and Budapest to give you a lot of variety and a lot of reach.

There is a book called "Europe by Eurail" that may help you figure out some good base cities based on which countries you want to visit and what you want to see there. I know, I know, the dreaded Eurail, but you don't have to do it with a eurail pass. I used the book just as a research tool because it lists something like 25 base cities and three or four other places you can easily visit from each of them by train and also the train connections between the base cities and the length of each segment. It's easy enough then to go to the individual train companies for each country and get actual timetables and prices of point to point train journeys. And you can go online or get a guidebook for each country to find other possible day trips from your chosen base city/cities. I found it a helpful tool, along with guidebooks - lots of guidebooks - and forums like this. The more tools you have the better prepared you will be.

Let's put this into perspective. . . . in square kms.
France 644,000
Germany 357,000
England 130,000 (without Wales, Scotland or Northern Ireland)
Texas 696,000

Italy 301,000 (length 736 miles)
California 424,000 (770 miles)

Trains are very good in much of those countries but the fast trains that make day trips possible to larger cities are expensive. Small towns are usually not covered by them.

All that being said, you can certainly find cities that offer lots of varied attractions plus interesting day trips to small towns and other points of interest that would fill up a week, maybe two, depending on your interests. But to give recommendations, I'd need a whole lot more information - what interests, how many days, budget, time of year for a start.

London is a great base! Plenty to see and do (no matter your interests) on days you stay in the city, and lots of good rail (and bus) access for day or overnight trips. Here are just some of the places we've enjoyed doing as day trips from London (yes, some can be great destinations for several days, but day trips will give you a good taste):
Windsor, Bath, Stonehenge (can be done from Bath) Cardiff Wales, Stratford-upon-Avon, The Cotswolds (can be done from Stratford-upon-Avon), Winchester, Canterbury, Dover, Brighton, York, Edinburgh (a bit of a stretch, but it can be done).

Plenty of other places, too. We haven't 'done' Oxford or Cambridge, Leeds castle, or other very popular sites, so I can't say anything about them- but there are lots!!!

Stonehenge, Cardiff, The Cotswolds, York, Edinburgh are not really feasible as day trip options from London. They are just too far.

djp_syd actually i understand that on the autumnal equinox that there is a point at Stonehenge that will take you anyplace in the world in seconds.

James, it's easier just to fly to Budapest instead of shlepping to Stonehenge ☺

James, are you saying I should have the spare room ready for you in 3 weeks ??

David, it would be a pleasure.

France is the same size in square miles as California. More or less. Germany is the size of Montana. England is the size of Illinois. Adjust your expectations accordingly.

You have received many responses, but maybe not what you are looking for. The big question seems to be: Are you just considering Day Trips? or are you considering overnight or trips of 2 or 3 nights as well? Also, what is your time frame? week, two weeks, month, two months? Both these questions make a big difference.

As someone mentioned, for day trips, your radius is short. If you have time and want to do a few days per trip, then possibilities increase dramatically.

In the case of willing to have a base and do trips of several nights, then look for a town with great rail service, access to an airport with good budget flights, and if needed someplace that you could rent and park a car. Someplace near Frankfurt (am Main) for example would be a possibility...few hours into Paris, good access to Southern Germany and Switzerland, North to Amsterdam and Belgium, Berlin, all by train. Considering air, you get decent routes to Eastern Europe, Spain, Southern France, Italy, London, even Croatia. It also has the benefit in that there is plenty to do just as day trips in the area, within an hour or two of travel.

James and David - y'all should meet in the middle . . . here where it all started ☺

Chani, you are in South Africa?