The McDonald Farm is a historic agricultural complex near the city of Xenia in Greene County, Ohio, United States.

It has been named a historic site, largely because of a quarry on the farm, which supplied stone for the Washington Monument.

[2]: 380  Wilford McDonald, who lived about 3.5 miles (5.6 km) south of Xenia,[2]: 381  began quarrying limestone from his farm around 1820,[3] after it was exposed by erosion from a nearby small stream.

Quarrying revealed limestone deposits as deep as 8 feet (2.4 m) in some places, much of it smoothed by glacial abrasion.

The reputation of McDonald's quarry became more prominent than any other source of Greene County limestone;[2]: 381  before concrete became prominent as a building material, McDonald supplied substantial amounts of limestone for Xenia buildings, and some of his stone was transported to farther localities.