Venice, Trieste, Slovenia, and Croatia

My wife and I just came back from visiting our older son, who has been on a college work-study this Summer in Venice and Trieste, and then taking a trip to Slovenia (Ljubljana, Bled, Postojna Cave) and Croatia (Pula, Rovinj, Plitvice Lakes, Split, Dubrovnik). It was a delightful trip, even beyond just seeing our son. A few thoughts:

1. Most impressive man-made sight: Venice. Yes, it's full of tourists, but there's a reason for that. A City of Islands, a citypelago, unlike most other places on earth.
2. We spent three days in Venice, but no-one offered us any Dogecoin.
3. Most impressive natural sight: Postojna Cave in Slovenia. Glorious.
4. Leibniz cookies, continental Europe's answer to the Fig Newton.
5. Best meals, from cheapest to most expensive: Geco Pub in Trieste; Ćiri Biri Bela in Split; Arsenal in Dubrovnik; Bled Castle Restaurant in Slovenia.
6. In Trieste, we stayed on Viale 20 Settembre. (a) What's the significance of September 20? (b) That street name, unsurprisingly, is seen in many Italian cities; why is it somewhat ironic in Trieste?
7. It was very easy to get around in English (admittedly, in the relatively touristy places we visited), and the people were generally very friendly.
8. Dubrovnik in Croatia was once the Republic of Ragusa, with the motto "Non bene pro toto libertas venditur auro," meaning "Liberty isn't worth selling for all the gold in the world." Good sentiment! Also, winter is coming.