Geneva 15.7%. Of the agricultural land, 0.3% is used for growing crops. Of the water in the municipality, 0.2% is composed of lakes and 2.9% is rivers and streams. The altitude of Geneva is , and corresponds to the altitude of the largest of the Pierres du Niton, two large rocks emerging from the lake which date from the last ice age. This rock was chosen by General Guillaume Henri Dufour as the reference point for surveying in Switzerland. The second main river of Geneva is the Arve, which flows into the Rhône just west of the city centre. Mont Blanc
Conservatory and Botanical Garden of the City of Geneva Conservatory and Botanical Garden of the City of Geneva The Conservatory and Botanical Garden of the city of Geneva () is a museum and an institution of the City of Geneva. It was founded in 1817 in a former area of "Bastions Park" in 1817 by Augustin Pyramus de Candolle. The Botanical Gardens were transferred to the Console site (192 rue de Lausanne) in 1904, constructed by the Genevan architect Henri Juvet in 1902–1904 specifically to house the Delessert herbarium held at Bastions. The collection grew in 1911–1912 with the gift of the Emile Burant herbarium, then again in 1923–1924