The Jet d'eau in Geneva, Switzerland.
A vertical mounting stream of water, creating a water pillar of up to 140 meters high.
Le Jet d'eau, which is its name in French, is probably the most important tourist attraction in Geneva. (There aren't that many. ;-)
The Jet d'eau also serves as a wind indicator for both sailors on the Lac Léman and for paragliders and hanggliders soaring around the nearby mountain Le Salève.
The first Jet d'eau was part of the hydroelectric station on the Rhône river which is the water outlet for Lac Léman. This station was built in 1886. There was a need for a security valve for over pressure water and the Jet d'eau was built for this purpose. The water column could reach 30 meters above ground level.
In 1891, the Swiss realized that the Jet d'eau had become a tourist attraction and it was moved to the Geneva harbor, in the south-west part of Lac Léman.
This part of Geneva is a lot more visited by tourists and the Jet d'eau is seen from within the center of the city plus from many surrounding heights and mountains.
The Jet d'eau of Geneva then reached up to 90 meters above the surrounding water level in the lake.
After a major overhaul and important modifications finished in 1951, the water pillar now reaches up to 140 meters above the water level.
The Jet d'eau is normally turned on in early March and turned back off in mid October. It's also turned off during night time, which for the Swiss starts around 11:00 PM.
For security reasons, it is turned off during days with strong winds or when an unfavorable wind direction would project the water either on the nearby streets or on the boat traffic.