In a country of real castles, Pehryn, in Bangor, on the edge of Snowdonia National Park, is a fabulous fake. Built in the 19th century, a fantasy castle home for a prosperous family, it is now owned by the National Trust. Penryhn's walled gardens shelter a surprising range of tropical plants - palms, maidenhair trees, jasminium climbers and Chinese gooseberries.

