The Loudoun Valley is a small, but historically significant valley in the Blue Ridge Mountains located in Loudoun County in Northern Virginia in the United States.

Aldie is an unincorporated community and census-designated place (CDP) located between Chantilly and Middleburg in Loudoun County, Virginia, United States. The historic village of Aldie is located on the John Mosby Highway in a gap between the Catoctin Mountains and Bull Run Mountains, through which the Little River flows. Aldie traditionally serves as the gateway to the Loudoun Valley and beyond.