According to Wiktionary, (https://goo.gl/lrRr4B) the Turkish word kale comes from the Arabic word qal‘a (قَلْعَة) meaning ‘castle’ or ‘fort.’
Apparently, the origin of the word ‘castle’ is a little bit unclear, it is a borrowing from the Late Latin word castellum, a diminutive of castrum. The Latin word castrum maybe comes from the Proto-Indo-European root *kat-, meaning ‘hut’ or ‘shed.’ It also maybe related to the Gothic word hēþjō (
I answered "the students in the castle", after the previous question, "Ankara'da güzel bir kadın" [or so I recall, unfortunately DL does not provide a way to go back to a previous question, or do they?] was to be translated "a pretty woman in Ankara", rather than "there is a pretty woman in Ankara". Why is "the students in the castle" wrong, and how would you say that in Turkish, please?
For "the students in the castle", we can only say "kaledeki öğrenciler". Here as you can see, there is not a verb. And the emphasis is on "the students", the students who are/were/have been in the castle. The verb to be is not here. So we say like that. And your example is true.