Arnor- Designed For Failure?

[Puddleglum]

Originally Posted by Inziladun

I still wondered, too, why Gondor got an indestructible tower and similar wall, while Arnor lost out.

It may also be that these structures were fashioned from geologic features (as Fonstad suggests in "The Atlas of Middle Earth"), perhaps the remnants of a basaltic flow which the Numenoreans simply worked and carved, rather than "built" from scratch.

"Gondor" does, after all, mean (literally) "Stone-Land" and so would be more likely to have such features to be used and shaped than Eriador (where Arnor was established).