In Lamentations 2:15, passersby mock Jerusalem as the city once called what?

Answer: The perfection of beauty

They hiss and shake their heads: "Is this the city that was called the perfection of beauty, the joy of all the earth?"

“All who pass by clap their hands at you in scorn. They hiss and shake their heads at the Daughter of Jerusalem: “Is this the city that was called the perfection of beauty, the joy of all the earth?””— Lamentations 2:15 (BSB)