The Saint Louis Art Museum is home to one of the most comprehensive art collections in the US and is located in the city’s Forest Park. The original and main building, designed by Cass Gilbert, was built as one of the exhibition pavilions for the St Louis World’s Fair, held in 1904. Five years later it became the new home of the city’s art collection. Significant growth in the collection over recent years, combined with the ever-growing size of contemporary artworks and the need for increased below-ground parking provision as part of the park’s restoration, led to a major new commission to improve the museum.

The new East Building accommodates the museum’s modern and contemporary art collections, together with temporary exhibition spaces, a new museum shop and a significant dining space. It respects the position of the Cass Gilbert original as the focal point in the park and presents itself as a single-storey pavilion that steps out and back in four directions, keeping its visual impact on the immediate surroundings and its wider environment to a minimum.

The building sits on a low plinth that reconciles the surrounding topography of the park while also aligning its internal level to the main floor of the Gilbert building. It also establishes two connections through the existing south-east and south-west doorways, respecting the existing axiality. Four large floor-to-ceiling windows provide views towards the Grand Basin, the park and the newly landscaped garden. This landscaping is an important aspect of the project and features a new entrance, a forecourt and a sculpture gardens that blend into Forest Park. The façades are panelled with dark concrete containing local aggregates that was cast and polished on site, giving the pavilion a solid presence among the trees.

The pavilion is topped with a concrete coffered ceiling spanning the entire space. In addition to its role as a structural grid, the ceiling modulates and filters daylight into the space. The system works as a result of the depth and colour of the coffers and the layering of materials in between: translucent glass on top and a multi-layered light diffuser below. The coffered ceiling articulates a strong material presence and allows the internal walls to be relocated according to the module of the grid, creating a degree of flexibility for the arrangement of the galleries. Thresholds between the gallery spaces are defined by absences of walls rather than by doorways, allowing for uninterrupted views through the galleries and out to the landscape beyond.

Infrastructure facilities and circulation improvements, although largely hidden, formed a significant part of the project. The provision of 300 parking spaces and the creation of direct connections around the site to the new and old structures was also important. The old sculpture court, for example, can now be reached from the new car park via a grand staircase, followed by a promenade passing a canteen and a sunken courtyard filled with Andy Goldsworthy’s imposing Stone Sea – a specially commissioned sculpture that forms an integral part of the new development.