Festspielhaus Bregenz, Opera house and convention center in Bregenz, Austria.

The Festspielhaus Bregenz is a performing arts and convention complex on the shore of Lake Constance in Vorarlberg, Austria, housing a main theatre hall, an opera area, and several conference rooms. It sits directly next to the Seebühne, the open-air floating stage on the lake, forming a single connected venue area with it.

The Festspielhaus opened in 1980 to give the Bregenz Festival, which had been running since the 1940s, a permanent indoor venue. Before it was built, most events were tied to the summer season on the open-air Seebühne, with no covered space available for year-round use.

The building is run by Kongresskultur Bregenz GmbH, a wholly owned subsidiary of the city, and hosts the Bregenzer Meisterkonzerte concert series, the Bregenzer Frühling dance festival and concerts by the Symphonieorchester Vorarlberg alongside the summer festival. Its roof carries Cerith Wyn Evans's white neon installation reading "299.792.458 m/s", the speed of light, visible as reflection in the windows and the lake water.

The building is fully accessible and easy to reach on foot from central Bregenz, with public transport stopping nearby. During the main festival weeks in summer, the area around the venue fills up quickly, so arriving early gives you time to explore the lakeside before any performance.

On the roof, artist Cerith Wyn Evans installed a white neon sign reading "299.792.458 m/s", the speed of light. It can be seen as a glowing object, as a reflection in the window panes and in the water, or as a shadow. The figure also appears in the raised lettering on the pale curved upper wall of the facade.