Incidentally, it looks like there is fairly regular bus service between Trieste and Ljubljana (about 1.5 hours away), which could add another link to the Trieste hotspot (which I'd recommend keeping unless cross-border traffic on public transport really is no longer feasible).

You are right. That works and makes Triest 4 WHS in any case. Technically Venice is also well within reach.

Re caves: I think they are feasible, but quite strenuous for the distance involved. But 20km is within renting a bike distance.

Why 4 can't it have 5-9
Keep:
Aquileia: one hour by bus + train
Longobards; Cividale del friuli is 90m by train
Heritage of mercury: Idrija is 2h 30m on Rome2Rio with transfer in ljubliana and seems to have regular connection on the route (slovenia is schengen)
Add:
Ljubliana: 85m on bus
Venetian defense work: Palmanova is 50m by bus
Maybe:
Porec: seems to be direct bus in under 2 hours however croatia is not schengen
Skocjan Caves: Short distance however lacks regular transport as Slovenia is schengen its probably doable with taxi/Bike
Pile dwelling: Palu di Livenza takes roughly two hours but requires a taxi along with that I doubt anyone would travel that far for a pile dwelling when there are more accessible components (like in Zurich)
Beech forest: Snežnik – Ždrocle is 1 hour by train and 1 hour by taxi according to Rome2rio, I feel that is too long to be considered public transport

Some other neighboring hotspots that could be added
Brno<-> Vienna (90m)
Hiroshima <-> Kyoto (100m)
Stuttgart <-> Frankfurt (70m)
Brussels <-> Amsterdam (2h)
Florence <-> Rome (50m)
Nanjing <-> Hangzhou (80m)
I tried to keep these at maximum 2 hours as that would provide enough time to get to most other sites in a hotspot

I think we have to let go of the Silesia (Wroclaw) Hotspot.
I already deleted Tarnowskie Gory and should also do that with Auschwitz. Both are much closer to the Cracow Hotspot and already covered there. That leaves only 3 for Wroclaw. Did I overlook one?

Trier hotspot doesn't need to exist as all sites overlap
Add nice to Genoa hotspot as it is 2h30m by bus

* If there is a Genoa hotspot (missed it) it should be taken out of the other hotspots.


Rhineland Palatinate already gives an error. I am not fully convinced though. Trier, Lux, Völklingene and Rhine are one consistent area. Plus you have the Mosel...


Auschwitz belongs to Cracow. As I understand it, Germans specifically picked a location outside historically German regions for the death camp.

Tarnowskie is in Silesia. While closer to Cracow it should be listed in the Silesia Spot, too. It's on the border of both hotspots and i would argue we can keep both. And it can be done.

All of them are now covered by Nancy. It would be better to pick a different center for this, possibly Luxembourg, as most sites cluster to the north.

sorry i meant Turin not Genoa
we could create a Genoa hotspot with:
Cinque Terre (unconnected)
Genoa (centre)
Nice (unconnected 2h30m by bus)
Le Corbusier (Cabanon de Le Corbusier is 3h30m by train according to rome2rio
Maybe:
Vineyards of piedemont (2h30m but in other hotspots

Another unlikely one, that I propose to delete: https://www.worldheritagesite.org/connection/Ioannina+Hotspot
2 sites across a non-Schengen border. Only 1 bus a day found between Gjirokaster and Ioannina. Bringing a rental car across the border will be not permitted or very costly.

Pirin should be removed from thessanolinki hotspot as bulgaria is not schengen
Tunisia should become car dependent like Muscat and Peloponnese due to Ichekuel, Dougga and Kerkuane
Peloponnese hotspot's centre can be moved to athens as all sites are doable from athens by car and it is more accessible to most travellers.
Northern Vietnam and Sichuan Hotspot lack the "Cluster of at least 4 WHS within reach for a return day trip from a centre" that all other hotspots have
Washington D.C, Shush, Rio, Prague, Fujian, Kagoshima and Copenhagen lack that space in the middle that all other hotspots have

New hotspots that can be created with the car only rule that Muscat and Peloponnese have. (Times are from google maps)
Calgary:
Canadian rocky mountains: Banff is 90m
Head smashed Buffalo jump: 110m
Waterton peace park: 170m
Writing on stone: 210m
Dinosaur: 135m

Moncton
Miguasha: 217m
Lunenburg: 203m
Grand pre:180m
Joggin fosssil cliffs: 65m

Sydney:
Opera House: in city
Convict sites: in city
Blue mountains: just outside
Gondawa: barringtops is slightly less than 4 hours\

I think the rule laid out by Els is 4h public transport or 200km private car. In this case it 260km with 3.15h driving. So it would not be in. I think Sydney is hard, but it needs one more site.


Agreed. Not possible from Thessanolinki by public transport. 160km + border crossing also not a nice experience by car.


If you want to do it by public transport, Isthmus is the bus station for you as all components have busses from Athens that stop in Isthmus. That's why it's Corinth/Isthmus. And I think it should stay. In addition, Athens is decidedly not on the Peleponnes and nobody would be based in Athens and do multiple daytrips to e.g. Olympia, return and go from Athens to Mystras the next day.

But Bat, Al-Khutm and Al-Ayn is 244km from Muscat, is the limit 250km?
\
Your probably correct

Waterton and Writing on stone are way beyond 200km one way.