I also like the colour scheme on the flag of Zielona Góra, a city in Lubusz. The colours come from the city’s coat of arms. The green is presumably related to the city’s name, which literally translates to “green mountain”.
Poland, Western Poland, Lubusz Voivodeship, Gorzow Wielopolski, stained glass window of Gorzow Cathedrall, Cathedral Church of the Assumption of the Blessed Virgin Mary dating back to the thirteenth century. http://dlvr.it/KVNG3m