As I mentioned already, there are quite a few statues in Zagreb with brave men fighting&slaying snakes, dragons and other creatures.
When it comes to slaying a dragon, this has roots in old Slavic mythology. As much as a dragon represents "evil", it is also a life's necessity and a foreteller of something good to come. After reading stories about dragons it is easy to see parallels with the usual human behavior - from strength, viciousness, to kindness (e.g. if someone helps the dragon or its offspring).
In one of the stories, it is stated you had to kill a dragon in order to have spring and to get things growing/green again after a harsh winter.
This statue is in front of the Stone gate, the entrance to the Old town:
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