10-day trip this fall — love history, food, and architecture - Where?

Corfu, Rhodes and Crete all in Greece, have an interesting mix of architecture, history etc. Morocco also meets your criteria. Southern Italy is less touristy and is interesting. Malta, Cyprus, Montenegro, Croatia, Southern France also offer a lot of what you are looking for. And of course some of Northern Europe, maybe Denmark or Sweden. In the Uk the areas of Norfolk and Suffolk are interesting with old villages, churches and relatively free of tourists.

Hm, I am going to suggest somewhere offbeat, since you like Central Europe... how about ten days in and around Germany's Harz Mountains region? Lots of small towns including Quedlinburg, which is a UNESCO World Heritage City. See the ten million euro copy of the Gospels of Henry the Lion in the library in Wolfenbuettel. Or the beautiful painted facades of the square in Goslar. It goes without saying that all the little townships are full to the brim with lovely half-timbered houses, but of the north German kind. If you want to go further afield you could add Celle (painted designs on buildings) or Leipzig (music history).

Lavandula

ohhhh Lavandula, these towns you've suggested look amazing! Hope it's not hijacking to ask what would be the closest international airport? Perhaps Hannover or Leipzig?

Sounds like Italy to me.

Have you considered Bosnia? Sarajevo has a similar feel some of the places you love, it’s definitely off the beaten path, and provides beautiful nature, interesting little towns, nice people, and great value.

Montenegro would be another thought.

Based on the cities you visited and liked, Paris (yup, I know the tourists, but you gotta see it, just do it shoulder season), Lots of secondary Italian cities, Lviv, look at Sofia as it might interest you. Istanbul shoulder season, any of the Baltic capitals,

Don’t overlook Poland. Has you want for less $$ than other countries. Great train system.