Church of Sant Romà, 11th-century Romanesque church ruins in Vilanova de Sau, Spain.

The Church of Sant Romà is a Romanesque ruin near Vilanova de Sau, in the comarca of Osona in Catalonia, Spain, now largely submerged under the Sau Reservoir. The stone bell tower is the most visible part, rising above the water surface to a varying height depending on the season.

The church was consecrated in 1062 and served the local community for nearly nine centuries. When the dam was completed in 1962, the villagers of Vilanova de Sau were forced to leave, and the church was left to be swallowed by the rising water.

The bell tower rising above the water is a powerful symbol of loss for people in the region, as the entire village of Vilanova de Sau lies beneath the surface. When water levels drop sharply, parts of the old village streets and wall remains reappear alongside the church.

The tower is most visible during dry periods when water levels drop and more of the stonework is exposed. The area is fenced off for safety, so the best views are from the marked observation points along the shore.

In 2021 the Official World Record Organisation, with the University of Barcelona's heritage education research group, recognised Sant Romà as the oldest standing submerged church in the world. The bell tower's tip stays above water even when the rest lies 23 metres deep, and it is read as a gauge of reservoir levels.