Here is a manhole cover from Freiburg, BW ("Freiburg im Breisgau"), Germany. It features the city seal (see
here) from the 13th century, one of the oldest in Germany.
Side note: There is another connection between that seal and "water" in Freiburg. In the 1890s the city built a container for drinking water called
Wasserschlössle - actually a little château d'eau.

The design was inspired by the city seal ...
Christian