快樂的蘿絲琳 Happy Roselin

The XXX logo can be seen everywhere in Amsterdam, such as t-shirts, garbage can, flag or even drain covers. However, what is the meaning of XXX in Amsterdam? XXX symbol stands for fire, floods and the Black Death. They display the three dangers and remind us to ward off these hazards so that we won't repeat the same mistakes.

Unfortunately this is not the truth. The truth is it's a St Andrews cross means valiant, steadfast and compassionate. So now you know. Honestly I like the first theory more than the second one.