D.C. Boundary Stone NE No. 1

Washington, DC · est. 1947

On June 3, 1880, Alexander Graham Bell transmitted speech through the air on a beam of light—not a wire—using his newly invented 'photophone,' sending a wireless voice message from the top of this building to a receiver blocks away. Bell considered the photophone among his most important inventions, though the world was not yet ready to use light for communication. The plaque was placed in 1947 to mark the centennial of his birth.

Chevy Chase, MD

In 1774, on the eve of the Revolution, Thomas Johns—soon to serve as a colonel in the Continental cause—joined Georgetown merchant Thomas Richardson to raise flour mills along the reliable current of Rock Creek. Grinding grain into flour for the growing capital region, mills operated on this site for roughly a century, outlasting the men who built them and falling silent only in the 1870s. In an age before steam, a dependable creek was industrial infrastructure, and Rock Creek's waters turned the stones that fed Georgetown's wharves and tables.

College Park, MD · est. 2006

In 1914 the University of Maryland donated this College Park land for Maryland's first state tree nursery, where state forester Fred W. Besley — a student of forestry pioneer Gifford Pinchot — and head nurseryman Silas Sines Sr. pioneered large-scale tree propagation. Thousands of seedlings grown here reforested Maryland's woodlands and roadsides, healing land ravaged by decades of heavy logging and farming.

Washington, DC

The Mayflower Hotel opened in 1925 on Connecticut Avenue and immediately became a hub of Washington's political and social life, hosting Calvin Coolidge's inaugural ball as its first major event. Over the decades it entertained every president who followed and served as an in-town residence for vice presidents, cabinet members, Supreme Court justices, and members of Congress. Its Beaux-Arts grandeur earned it a place on the National Register of Historic Places.