Allentown, Pennsylvania is 24 times larger than Prospect Park (Brooklyn).
Area: 47 km2 calculated
Allentown is a city located in Lehigh County, Pennsylvania, United States. It is Pennsylvania's third most populous city, after Philadelphia and Pittsburgh, and the 224th largest city in the United States. Wikipedia
Area: 2 km2 calculated
Prospect Park is a 585 acres public park in the New York City borough of Brooklyn located between Park Slope, Prospect-Lefferts Gardens, Ditmas Park, Windsor Terrace and Flatbush Avenue, Grand Army Plaza and the Brooklyn Botanic Garden. Wikipedia