Prospect Hill was a mansion built in 1841 by successful contractor James Roach in Arlington County (then still named Alexandria County) in the U.S. state

U.S. state

A U.S. state is any one of the 50 federated states of the United States of America that share sovereignty with the federal government. Because of this shared sovereignty, an American is a citizen both of the federal entity and of his or her state of domicile. Four states use the official title of...

 of Virginia

Virginia

The Commonwealth of Virginia , is a U.S. state on the Atlantic Coast of the Southern United States. Virginia is nicknamed the "Old Dominion" and sometimes the "Mother of Presidents" after the eight U.S. presidents born there...

. The house was built on Arlington Ridge Road. The house was demolished in 1965, but an historic marker has been placed at the site.

Prospect Hill has been recognized as an Historic District by Arlington County.