MVRDV and Zecc Architecten have won the competition to turn St. Francis of Assissi Church in Heerlen, built over a hundred years ago and offering religious services until 2023, into a public swimming pool for the Dutch city.

A key feature of the project, nicknamed ‘Holy Water,’ is the adjustable pool floor, which can be raised to different levels, even to the point of concealing the water entirely, resulting in a multifunctional flat surface for hosting different social and cultural events. It can also be set to hold a shallow layer of water, creating a unique atmosphere.

The lighting over the pool was inspired by the church’s original lamps, as seen in period photographs. These are reinterpreted with four suspended rows of fixtures that also serve as lane markers for swimmers, in a fusion of history and functionality.

A main challenge is to guarantee efficient and sustainable climate control without jeopardizing the integrity of the historical elements. To this end, glazed partitions will delimit the pool space as well as protect the stained-glass windows and the artworks.

The original roof will be insulated from the outside to prevent excessive heat loss, while maintaining the view of the original brickwork from inside. The wooden ceiling structure will be retained and enhanced with sound-absorbing panels to improve acoustics. Technical systems will be integrated into the basement, freeing up the main space entirely for public use. Construction work is programmed for completion in 2007.