Apart from the home itself, the grounds of Oak Hall set it apart as a world class estate. Before Marshall & Fox began designing the lavish Colonial Revival mansion, Warren H. Manning, a Boston landscape architect, began to lay out the roads, trails, lawns, and gardens to emphasize the character of the site’s natural environment. Manning took advantage of the boulders on the glacial hill to build stone walls along the drive and a retaining wall for the formal garden. Some giant boulders were left in place as sentinels from the past.
He wrapped the hill in a winding drive that gives a commanding view of Penobscot Bay and exaggerates the height of the mansion’s columns as one approaches from below. Using the rural meadow to create expansive lawns, Manning emphasized the far-off views of mountains and ocean. He used massed plantings of native trees and shrubs – spruce, firs, arbor vitae, rhododendron, viburnum, spiraea, and honeysuckle – to provide definition and privacy. And the formal gardens close to the house provided beautiful detail and color.