The city's coat of arms is almost 700 years old. It shows Oslo's patron saint, St. Hallvard, sitting on a lion's head throne with a halo around his head. In front of the throne lies a woman that he tried to protect. In one hand he holds three arrows which killed both him and the woman. In the other hand he holds a millstone which was tied around his neck before his body was thrown into the Drammen fjord.
The drawing is surrounded by a circular inscription with the words UNANIMITER ET CONSTANTER OSLO, "united and constant Oslo".