Monaco is 320 times larger than Grand Army Plaza (Manhattan).
Area: 2 km2 World Factbook
Population: 30,508 (July 2014) World Factbook
Monaco, officially the Principality of Monaco, is a sovereign city-state and microstate, located on the French Riviera in Western Europe. It is bordered by France on three sides; one side borders the Mediterranean Sea. Wikipedia
Area: 0 km2 calculated
Grand Army Plaza lies at the intersection of Central Park South and Fifth Avenue in front of the Plaza Hotel in Manhattan, New York City. It stretches from 60th to 58th streets between East Drive and Fifth Avenue. The idea for such a plaza was first proposed by sculptor Karl Bitter in 1898. Wikipedia