Ellanor C. Lawrence Park, Nature preserve in Chantilly, Fairfax County, United States

Ellanor C. Lawrence Park is a 640-acre park in Chantilly, just north of Centreville on Route 28, deeded to the Fairfax County Park Authority in 1971. East of Route 28 stand Walney, an 18th-century stone farmhouse used as the visitor center, with 19th-century outbuildings, a smokehouse, dairy and ice house, plus Cabell's Mill and the stone house Middlegate. West of Route 28 lie playgrounds, athletic fields and a fitness trail.

In 1739 Willoughby Newton bought 2,500 acres around Centreville and leased 150 acres to Thomas Brown in 1742 under a three-lives lease requiring a 200-tree apple orchard and 530 pounds of tobacco yearly. By 1776 Brown and his son Coleman owned some 630 acres and likely built the stone house now the Walney Visitor Center. Lewis H. Machen bought 725 acres in 1843, used the stone house as a library, and his son Arthur named the farm Walney for the walnut trees in front of it. The land passed to Fairfax County as a 640-acre park in 1971.

The name Walney, given by Arthur Machen, refers to the walnut trees that grew in front of the farmhouse. Cabell's Mill, an 18th-century structure, is rented through the Fairfax County Park Authority for weddings, while Middlegate, an early 19th-century stone house, serves as park administrative offices.

Trails are mostly earthen and start from the Walney Visitor Center, the pond, Cabell's Mill and the northern terminus on Poplar Tree Road; trail maps are available at the visitor center. Bicycles are allowed only on the paved or gravel Big Rocky Run Stream Trail, which runs from near Cabell's Mill to the Fairfax County Parkway. Fishing in the pond and Big Rocky Run requires a state licence.

The wetland sections harbor bird species that visitors rarely see in other nearby locations throughout Northern Virginia. These marshy areas attract wading birds and uncommon species, making bird watching particularly rewarding.