http://www.krakow-info.com/hejnal.htm

Hourly bugle call from the tower of St Mary’s Church in Krakow
Every full hour a golden trumpet shows above Krakow’s central Grand Square in the west window just below the spire of the higher tower of the Basilica of the Virgin Mary's. Then a characteristic signal trumpet melody, known and dear to every Pole, resounds all over the city’s Old Town historical district. All of a sudden music comes to an abrupt end. Next the same bugle call is played towards the east, the south and the north. At noon the whole ritual is broadcast on the Polish national radio.

St. Mary's bugle call and trumpeter from Krakow
The Krakow signal bugle call, or Hejnal Mariacki, dates back to the Middle Ages when it was announcing the opening and the closing of the city gates. The bugler also played it to alarm his fellow citizens whenever he saw a fire or the enemy forces. And the melody abrupt ending is said to commemorate a trumpeter from Krakow who was shot through his throat by a Tatar archer in 1241 when the Mongols besieged the city.