Greenway Court is a historic country estate near White Post in rural Clarke County, Virginia. The property is the site of the seat of the vast 18th-century land empire of Thomas Fairfax, 6th Lord Fairfax of Cameron (1693-1781), the only ennobled British colonial proprietor to live in one of the North American colonies. The surviving remnants of his complex — a later replacement brick house and Fairfax's stone land office — were designated a National Historic Landmark in 1960.

Greenway Court was the center of the "Northern Neck Proprietary" or "Fairfax Grant", which passed to Thomas Fairfax, 6th Lord Fairfax of Cameron from his mother's family, the Culpepers, who had taken proprietorship of the land in 1673. Fairfax laid out the Greenway Court estate in 1747, intending it to be a much larger establishment than it became. The main house was a 1-1/2 story timber structure with long sloping roofs and corbelled brick chimneys. It was originally intended to house the land steward, but it was occupied by Fairfax with his nephew, Thomas Bryan Martin, until his death in 1781. Fairfax employed a young George Washington as a surveyor on his extensive land holdings.

Abandoned, the roof of the main house at Greenway Court collapsed in 1834, after which the structure was pulled down.