The structure lost its original function as a power source in 1963,[2] but it nevertheless continued to house pumping equipment to service Geneva's drinking water supply till 1988.

Towards the end of the twentieth century the BFM was converted into an entertainment venue, reopening in 1997 as an opera house / concert hall[2] designed by the architect Bernard Picenni in association with the acoustician Peutz and the scenographer dUCKS scéno.

The cantonal authorities therefore granted to the city a concession for exploitation of the "motor power" (in French "forces motrice") of the Rhône on 30 December 1882.

At the same time they embarked on the work necessary to regulate the level of Lake Geneva, notably by construction of a curtain weir across the river.

[citation needed] The project as originally envisaged involved building the Bâtiment des Forces motrices on land administered by the then separate municipality of Plainpalais (later subsumed into Geneva) which was in financial difficulties.

On the initiative of Jean-Daniel Colladon, the civil engineer Théodore Turrettini now embarked on a parallel career as a local politician, when he was elected to the Geneva city council.

Work on the structure began in November 1893, when the level of the lake and the flow of water through it was expected to remain relatively low for the next five to six months.

[citation needed] Five Jonval turbines were installed in the small wing of the powerhouse crossing the river and commissioned in May 1886, producing a combined power of 900 kW.

[5] The curtain weir was attached to the superstructure of the Pont de la Machine bridging the right arm of the river Rhône.

The chosen building material was strong enough to support the additional lateral forces introduced by the curtain weir into the structure.

Only the upper facade on the eastern end, facing the lake, reflected the extrovert decorated style of the interior, supplemented at the time by statues representing Neptune, Ceres and Mercury.

[citation needed] In order to avoid excessive pressure build-up in the hydraulic power network, a release valve was fitted beside the main hall of the powerhouse.

The three concentric arranged blade rings allowed to adjust the power of the turbine to the available drop height and the actual demand.

[citation needed] The Le Bâtiment des Forces motrices lost its principal original functions during the 1960s, as manufacturing industry moved out to the edge of the city.

After various meetings with the responsible city department, and thanks to the generosity of a locally based benefactor, the decision was taken to adapt the main building as a 1,000-seat auditorium suitable for theatrical uses.