What is it called?
 

This is, I daresay, a very stupid question. But does the city in Gondor that has Minas Tirith in it have a name? Or is it just called the White City?

The city of Minas Anor was renamed Minas Tirith after the fall of Minas Ithil in TA 2002. The White Tower is in the Citidel (seventh level) of Minas Tirith.