Bryn Athyn Cathedral

Bryn Athyn, PA · est. 1972

In 1924 aviation pioneer Harold F. Pitcairn established his first flying field on this site, launching decades of experimentation in flight. He and his associates developed the American autogiro—an aircraft with a free-spinning rotor that pointed toward the eventual helicopter—and won the prestigious 1930 Collier Trophy for the achievement. This quiet Montgomery County ground was an early laboratory of American aeronautical innovation.

Philadelphia, PA · est. 1994

Perched above the Pennypack, Knowlton was designed in 1881 by Frank Furness, among the boldest and most inventive American architects of the Victorian age, for banker William Rhawn. With its muscular massing and idiosyncratic ornament, the country house broke from convention and helped redefine what a modern American home could be. Furness's daring style would influence a generation, including a young draftsman in his office named Louis Sullivan.

Cheltenham Township, PA · est. 2006

In 1795 Benjamin Rowland, Jr. founded a mill complex near here that turned out high-quality shovels and spades for a young nation. Run by the Rowland family until 1901, the works earned an international reputation and helped prove that American-made goods could compete with the finest from abroad. The surviving Rowland house is among the last 18th-century structures tied to early American hardware production.

Cheltenham Township, PA · est. 2005

Drawn to Philadelphia by the 1876 Centennial, Cyrus H. K. Curtis stayed and built a publishing empire, the Curtis Publishing Company, whose Saturday Evening Post and Ladies' Home Journal reached millions of American households. From 1891 until his death in 1933 he lived nearby at Lyndon, an estate whose Frederick Law Olmsted-designed grounds now form the public Curtis Arboretum. Only Curtis Hall, the home's music room, still stands.