Concierge.com's insider take:
The subtropical Trevarno Gardens are at the center of a 750-acre estate that dates to 1246—grounds that also encompass a lake with a Victorian boathouse, and acres of woodlands for peaceful ambles. Visit in April and May, when the valley becomes a sea of bluebells (Trevarno, Crowntown, near Helston, Cornwall; 44-1326-574-274; www.trevarno.co.uk). In a 26-acre ravine, Trebah Garden is filled with palms and banana trees, streams, and waterfalls. Views extend to a beach on the Helford River 200 feet below (Mawnan Smith, near Falmouth, Cornwall; 44-1326-250-448; www.trebahgarden.co.uk). The Lost Gardens of Heligan were considered one of the finest plantings of 19th-century England, but the grounds fell into decline during and after the two World Wars (only a few members of the 22-man garden staff survived World War I). In the 1990s, a restoration program began resuscitating the land, and today, 80 acres of restored formal gardens, entwined with paths and dotted with period features, such as the original summerhouses, are open (Pentewan, St. Austel, Cornwall; 44-1726-845-100; www.heligan.com).