Old Botanical Garden, Zurich, Botanical garden near Schanzengraben moat, Zurich, Switzerland.

The Old Botanical Garden Zurich is a public garden in the center of the city, next to the Schanzengraben moat, with plant beds, pathways, and glasshouses dating from the 19th century. It is listed as a class A Swiss cultural property of national significance, placing it among the most protected sites in the country.

The garden was founded in 1837 by gardener Leopold Karl Theodor Fröbel, drawing on collections linked to the 16th-century naturalist Conrad Gessner. As the city grew, the garden was relocated more than once before settling at its current location.

The garden's name recalls the bastion 'zur Katz', whose guns were called Katz; the hilltop Gessner-Garten, opened on 27 May 1997, is a medieval herb garden honouring Conrad Gessner. It shows around 50 medicinal plants, each with a quotation from a 16th-century healer such as Leonhart Fuchs or Hieronymus Bock. A memorial to Gessner stands at the garden's northern end.

The garden is easy to reach on foot from the city center and sits right next to the Schanzengraben. Admission is free, so it is easy to stop by at any time, though the glasshouses may have their own opening hours.

The garden's hilltop was the cavalier of the Bollwerk zur Katz, a raised gun platform whose long-range cannon could cover the lake shore as far as today's General-Guisan-Quai and the Sihlfeld toward the Limmat Valley. Two casemates, underground vaults for defence, formed part of the bastion's final stage of 1673–1675.