Recently listed in Time Out as the world’s most beautiful botanic display, Longwood Gardens, in Pennsylvania’s Brandywine Valley, might be thought of as a thousand-acre gallery of gardens. An international roster of designers has shaped its evolution, and now comes the unveiling of another transformation: Longwood Reimagined, a magnificent, 17-acre addition to its collection of gardens and conservatories. The cost: $250 million. The centerpiece of Longwood Reimagined is the new West Conservatory, which holds nearly an acre of Mediterranean gardens designed by the architects Weiss/Manfredi and the landscape architects Reed Hilderbrand. It joins a range of existing conservatories that overlook the spectacular Main Fountain Garden and its six acres of choreographed, dancing fountains. Says Marion Weiss, a principal at Weiss/Manfredi, this new structure completes the string of conservatories across the site’s Crystalline Ridge. The evocation of landscape is no accident. It is part of a deliberate design strategy to weave together new and old in a hundred different ways. —Lewis Jacobsen