Philadelphia will welcome a groundbreaking new cultural destination on September 21st, 2025, with the opening of Calder Gardens, a unique park and museum complex designed by renowned architects Herzog & de Meuron in collaboration with celebrated landscape designer Piet Oudolf. Rather than creating a traditional monumental museum structure, this innovative project presents Alexander Calder's artwork within a lush, carefully layered landscape that gradually reveals its architectural structure and gallery spaces as visitors move inward from the city.
The project takes root in a city deeply connected to the Calder family's artistic legacy. Alexander Calder's grandfather and father both made significant contributions to Philadelphia's cultural landscape, and works created by all three generations of the Calder family can be found along the famous Parkway. From the Parkway, visitors encounter a long tapered metal wall that forms an austere backdrop to the meadowed garden, effectively softening the sounds of nearby traffic while leading visitors to a wood-lined entry point situated beneath a distinctive folded metal canopy.
The architectural design remains deliberately understated and thoughtfully integrated with its surroundings. A circular disc positioned at the center of the complex creates an open plaza while concealing the main gallery spaces below ground level. Two strategically placed sunken gardens—one featuring a perfectly round design and the other displaying an irregular, more organic form—bring natural daylight into the underground galleries and provide distinct, carefully curated settings for displaying Calder's sculptural works.
Inside the museum, visitors descend from a modest lobby to explore a series of Herzog & de Meuron-designed galleries that vary dramatically in lighting conditions and spatial proportions. The Highway Gallery offers visitors elevated views of Calder's famous mobiles from a specially designed mezzanine level. The Open Plan Gallery, positioned beneath the central disc, receives abundant natural light and frames carefully composed views of the adjacent Vestige Garden. Smaller, more intimate spaces including the Apse and Curve galleries provide appropriate settings for displaying Calder's works on paper and light-sensitive sculptural pieces. The architects have planned each room to encourage slow, careful, and contemplative encounters with Calder's diverse body of artistic work.
Jason Frantzen, senior partner at Herzog & de Meuron, describes the ambitious project as functioning both as "an actual and a conceptual garden," designed through close collaboration with the Calder Foundation and the Barnes Foundation. The goal is to honor Alexander Calder's artistic legacy while simultaneously creating an accessible space where all Philadelphians and visitors from around the world can discover and rediscover Calder's work through repeated visits.
Piet Oudolf's masterful 1.8-acre landscape design surrounds and threads throughout the architectural elements of Calder Gardens, successfully transforming a once-overlooked urban site in Philadelphia into a dynamic, shifting meadow that changes dramatically through all four seasons. More than 250 carefully selected plant varieties—including various grasses, perennials, and native woodland species—form a living composition that continuously changes with weather patterns and the passage of time. Thoughtfully designed paths curve through established woodlands, expansive perennial meadows, and tall planted borders, drawing visitors naturally toward the central disc while framing new and unexpected views at every step of their journey.
The landscape features range from the West Woodland Gardens' young oak trees to late-summer prairie grasses that sway gracefully near the building's edge, with Oudolf's expert planting design encouraging visitors to adopt a slow and contemplative pace throughout their visit. The sunken Vestige and Sunken gardens, which remain visible from the main gallery spaces, represent a living hybrid of art and landscape design. As Oudolf emphasizes in his design philosophy, "Gardens are for everyone."
Designboom visited Calder Gardens on September 15th, ahead of its public opening, to experience firsthand how Piet Oudolf's carefully crafted meadows engage in dialogue with Herzog & de Meuron's understated architecture. The preview revealed a harmonious integration of landscape, architecture, and art that promises to offer visitors a unique and transformative cultural experience when it opens to the public.
