This is a Royal Copenhagen, Denmark plate, dish, butter pat, plaquette or tea bag holder in blue and white depicting Kobenhavns Radhaus, which is a building in Copenhagen, Denmark.

The small plate is made of alumina faience and was made between 1903-1930. The little plate is 3 inches in diameter.  

These little souvenir plates could be used to hang on the wall with the hole in the rim at the back, hold a tea bag or butter or sit as a decorative pin dish to add color.

The dish is in excellent used vintage condition with no chips, cracks or wear. Lovely!