The Schanzengraben is a canal that connects Lake Zurich to the Limmat, through the western end of central Zurich. The canal was dug beginning in 1642 as a part of a new set of defensive fortifications necessitated by the Thirty Years War. It was actually a moat, and the bridges across were wooden so they could easily be burned in times of trouble. Originally, it ran along what is now Bahnhofstrasse, but was rerouted in the 1860s as the area was developed.
The Schanzengraben is sunk 2m below Zurich's street level. The atmosphere along here is unique. In the summer, the trees overhead cast shadows It doesn't feel like you're in the middle of a major city. A walk along the canal (though not all of it is accessible) is one of Zurich's best walks.
Location: Border of Kries 1and Kries 2