City of the Kings
The City of the Kings was a name used for two royal cities of the Dúnedain at different times in history. It originally referred to Armenelos, the capital of Númenor, which was the seat of the island's Kings (and Queens) throughout its history.
The same title was later applied to Minas Tirith in Gondor (as in the quote above), where the Kings of the name were the many generations of the Kings of Gondor. Historically, in fact, Minas Tirith had not been the City of the Kings of Gondor throughout their entire history. Their royal residence was originally in Osgiliath on the Anduin, but the seventh King, Ostoher, took Minas Anor (as Minas Tirith was then known) as his summer residence. It only became the absolute royal seat of Gondor long afterwards, when the twenty-seventh King, Tarondor, moved the court permanently to Minas Anor under Mindolluin.