The grounds of the museum are set within the wider landscape of the valley of the
River Avon and has fine views over the valley towards the village of Limpley Stoke and the
Kennet and Avon Canal. Garden features include a small
grotto with a water spout. The museum gardens include extensive renovated areas representing trends in both English landscape and American garden design. The American Museum originally employed
Lanning Roper to design a mixed border, but since the museum opened in 1961, the 30 acres around the house have been developed to include a replica of
George Washington’s garden at
Mount Vernon, as well as a Lewis and Clark trail, and an
arboretum that includes a collection of American trees. The Mount Vernon Garden, which is a re-creation of a part of
George Washington's garden at
Mount Vernon, is situated away from the house on the site of a former Italianate garden and was opened on June 26, 1962. In 2018 the Mount Vernon Garden was restored to replicate more closely the original layout implemented by George Washington. With the addition of the New American Garden, officially opened on September 15, 2018, as part of a £2 million project to renovate the lawn and
herb gardens immediately adjacent to the manor house, the museum grounds now boast the largest collection of American horticultural features in the United Kingdom. This project was the first European commission for the American landscape architects based in Washington D.C., Oehme van Sweden (OvS). The planting in the New American Garden follows the free-form style made famous by the firm's founders, Wolfgang Oehme and James van Sweden. Native American shrubs, perennials, and bulbs feature heavily, but the garden is designed to work with the steep terrain and enhance the view over the Limpley Stoke Valley, which is a designated Area of Outstanding Natural Beauty (AONB). The new garden path, known as The Winding Way, is a fully accessible pathway encircling the lawns and American Rose Collection, as well as the natural amphitheatre, which has become the museum's outdoor theatre and events space. == Governance ==