Longwood Gardens, in Kennett Square, Pennsylvania. Designed and constructed by the horticultural staff of Longwood Gardens. It's one of the premier horticultural display venues in the world, was first established as an arboretum in 1798 by Joshua and Samuel Peirce.
The land and its arboretum was purchased by Pierre S. du Pont in 1906 to preserve the trees, and Mr. du Pont personally oversaw many of the improvements until the Gardens were turned over to a foundation he set up in 1946. While the exterior gardens enjoyed an international notoriety early in this century, Longwood Gardens is now equally well known for its indoor displays.