Hertfordshire is lucky to have an abundance of formal parks and gardens, like those at Ashridge and Hatfield House, as well as those tended by the local authorities in public parks - even roundabouts! And of course there are all those gardens and allotments cared for by entusiastic gardeners.
Capability Brown
design for Youngsbury, Standon, 1770
The Gardens of Fanhams Hall, Ware
Photo gallery of the Formal and Japanese gardens