In the 20th century, New York for sure.
London and Paris second and third respectively. Although all three are equally iconic tbh as everybody knows them. Ny is only first due to Hollywood.
Rome for the thousands of years it ruled the world.
Cairo too.
London in the era of the British empire. Constantinople/Istanbul at its peak...
It's a stupid question because all cities known, and in Asia for instance Hong Kong would be better known. Whichever country you're in, the capital will be the most iconic city to its people. NYC is winning because the majority of ATRLers are American.