[mesmark]

"I visited the place which was Korea."

This was the answer a student gave to a question that required them to rearrange the words. The answer was supposed to be:
"The place which I visited was Korea."

I have issues with the 'which' in the correct answer, but for the discussion here, I changed the question for everyone to "the place which is Korea."

Anyway, why doesn't this work with is? Naturally, we'd just say 'I visited Korea.' It seems that we wouldn't define which place by saying Korea, possibly because it's clear to all that Korea is a place. Does it have to do with the fact that it's a proper noun? Is it the 'the', indicating we already know the place? everything?

What do you think?