Longwood Gardens, a botanical visitor attraction near Philadelphia, US, has revealed plans for a US$250m redevelopment project.

The historic site – one of the largest horticultural gardens in the US – will transform its visitor experience through the revitalisation of 17 acres of its core conservatory area.

The 'Longwood Reimagined' project – set to be completed by late 2024 – will expand the public spaces of the central grounds and connect them from east to west.

Existing services will be improved with the introduction of new buildings and garden areas, as well as individual attractions.

At the heart of the plan is the building of a new 32,000sq ft glasshouse, designed by architects, Weiss/Manfredi and landscape architects, Reed HilderbrandReed Hilderbrand, with new gardens and pools.

Called the West Conservatory, the new structure will house a seasonally changing garden display, featuring islands, canals and low fountains.

"Built on the great 19th-century tradition of glasshouses and enhanced with new, sustainable technologies, our new West Conservatory will be the centrepiece and the largest component of the project," said CEO, Paul B Redman.

"Like many of Longwood’s renowned features, it has a close relationship with water and seamlessly integrates the old with the new.

"Its asymmetrical peaks will rise from a pool on which the entire building will seemingly float, while its islands of interior Mediterranean-inspired gardens will be set amid pools, canals, and fountains in an exquisite tapestry-like design."

Other projects to be undertaken as part of the reimagine works include the relocating of the Cascade Garden, a new Bonsai Courtyard and the redevelopment of the Waterlily Court.

Redman said: "Think of an art museum collecting the works of Picasso and Monet – we're doing that for landscape architecture and garden design.

"Now, our legacy of innovation continues as we embark on the most ambitious expansion, reimagination, and preservation of our Conservatory and surrounding landscape in a century.

"With the realisation of Longwood Reimagined: A New Garden Experience – a sweeping reinvention of 17 acres of our Conservatory and grounds – we are honoured to enhance, steward, and preserve one of the world’s most important, most beautiful collections of gardens and glasshouses.

"Stunning new buildings, wondrous new indoor and outdoor gardens, surprising new guest experiences, and much more await. We’re expanding our grounds, connecting them from east to west in a beautiful, unified journey of lush, formal gardens to open meadows to winding paths to breathtaking Brandywine Valley vistas."