The flag consists of three color bands.
The colors of the bands are:
black on the top, red in the center,
and yellow on the bottom.
Black and yellow were the colors of
the Habsburg Monarchy
and the Austrian Empire.
The red in the middle is from the color　
of the Hanseatic League.

  The Hanseatic League （ハンザ同盟）：
中世後期に北ドイツを中心にバルト海沿岸地域の貿易を独占し、
ヨーロッパ北部の経済圏を支配した都市同盟