I don't know what you mean by central Paris, but if what you are saying is that if one stays in the geographic center of Paris, than you can walk everywhere, then even putting aside that I usually stay in Montmartre, someone staying in the 8th who wants to walk to the Jardin des Plantes in facting a walk of nearly 90 minutes. The walk from the 7th to Sacre Couer is more than an hour. Does no one visit St Denis or the Bois de Boulogne?

I meant to add Berlin to the cities of Europe that I think one doesn't really understand if one doesn't take public transport a few times while there.

I also realize that for many people, the novelty of travel is walking. They drive everywhere while at home. Maybe especially wallking in a safe city is a joy in itself (I agree with this). Just letting people know that the public transport systems of Europe -- trams, buses, funiculars, underground, navettes, boats and some taxi rides -- are worth experiencing.

I walked everywhere in Paris too...from Saint Gemain-de-Pres to the Eiffel Tower and to the Arc of Thriumph which were the farthest places I walked, it was about 2 miles/each in different directions of course, you will have to take the train to Versailles Palace though...

I think one of the issues is that everyone includes the Eiffel tower which is sort of an outlier in terms of major sights.

That said we have walked a lot in both places. The difference is that in paris the Metro is convenient, inexpensive and there are stops everywhere. In Rome there is no similar easy to use everywhere public transit.

I've spent a lot of time in Rome and a fair amount of time in Paris and I think both are very walkable cities. If you enjoyed walking in Rome, you will probably feel the same in Paris. I almost always opt to walk unless I'm in a hurry. It helps me justify all the rich food I'll be eating.

That said, Paris has a fantastic Metro system while Rome does not. Hopping on and off the metro can be quite a time saver (unless yes, you are going through one of those massive stations where a walk from one line to another can take 15 minutes and cover half a mile).

I'll also be in Paris in March and I plan on buying a weekly Navigo Pass. I like the option of taking the bus or Metro if I'm tired or if it's raining, and it will cover our return to CDG as well.

I think Rome is much more compact and walkable than Paris- and it took me awhile and some exhausting days before I realized that a carnet of metro tickets would be my best friend in Paris. Of course, traipsing through the connections on the Paris Metro is not for the faint of heart, but it provides great motivation to this 60-something to stay mobile so that I can traverse the system indefinitely.