The Polly Hill Arboretum will always be a secret garden. As it changes with the seasons, every encounter holds the magic of a new discovery. The arboretum, with its lichen-covered stone walls, expansive meadows, romantic arbors and rustic, historic buildings, leaves visitors with a real appreciation for the property when it was a sheep farm some 150 years ago. The leaves are turning now as days cool and nights come earlier.