Indestructible buildings?

[Trailhog250]

I have some starting buildings that must be indestructible for certain reasons but I cannot achieve this. As to why I don't know

The buildings require the hidden_resoucre hr_none. But I still can't seem to figure out the 'indestructibility' logic.

Must it be the first building of the settlement in the descr_strat?

[Gigantus]

Check the farms and roads entries in the EDB - it's the "hinterland" entry that makes a building indestructible.