In a creative adaptive reuse project, MVRDV and Zecc Architecten have won the competition to transform the St. Francis of Assisi Church in Heerlen, Netherlands, into a public swimming pool.
The transformation, aptly nicknamed “Holy Water,” breathes new life into the vacant church by giving it a new social function while carefully preserving its historic elements as a listed national monument. This innovative approach addresses the increasing number of visitors to Heerlen’s existing pools and revitalizes a recognizable silhouette in the city center. The project is also part of a larger city center development that includes a Roman museum and the renovation of the Royal-Rivoli cinema.
The design’s centerpiece is an adjustable swimming pool floor in the church’s nave, offering flexibility for various activities beyond swimming. In a striking feature, the floor can be filled with a thin layer of water to create a reflective surface, giving visitors the surreal experience of walking on water.
The design thoughtfully integrates the church’s history with modern elements. An illuminated circular canopy marks the main entrance, creating a contemporary connection between the past and present. Inside, visitors can access changing rooms and catering facilities, located at the rear of the church, through the original aisles. Glass walls separate these areas from the central pool space. Notably, the church’s pews will be reused within the glass walls, providing seating for swimmers and bar tables for spectators. The old pulpit will also be repurposed as a lifeguard’s seat.
The transformation balances the need to preserve the church’s historical integrity with the requirements of a modern swimming pool. The existing floor will be carefully removed to accommodate the pool, and a new mosaic floor, designed in collaboration with local artists, will complement the church’s colors, materials, and stained-glass windows, referencing Heerlen’s murals. Lighting above the pool draws inspiration from the church’s original lamps, with the rows doubling as lane guides.
A key design challenge was managing the pool’s humidity and ensuring energy-efficient heating while protecting the historic materials. The solution involves using glass walls to compartmentalize the pool area, safeguarding the stained glass and artwork. The church roof will be insulated externally to prevent heat loss, preserving the original brickwork view from the inside, and the existing roof covering will be replaced after insulation. Sound-absorbing panels will be added to the wooden roof to enhance acoustics, and technical installations will be discreetly placed in the basement.
“The vacancy rate of churches is increasing, so we need to come up with new, creative ideas for what we can do with these buildings,” says MVRDV founding partner Winy Maas. “Why not give these churches a social function again, as they used to have? A public swimming pool is ideally suited for this. Imagine: swimming the backstroke with a view of a church vault and stained-glass windows. By covering the entire pool area with a small layer of water, you can also create a beautiful visual effect, allowing the church to return to its original form and appear even larger and more impressive through the reflection.”
The design for Holy Water is a collaborative effort between MVRDV, Zecc Architecten, IMd Raadgevende Ingenieurs, Nelissen Ingenieursbureau, and construction economics consultancy Skaal. The first dive is anticipated at the end of 2027.