nfmungard:
and makes Triest 4 WHS in any case.
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