What event signifies the beginning of the cold war?

The cold war was a struggle between two superpowers the USA and USSR. It started in 1947 after the second world war. The cold war was marked by continuous rivalry between two former world war 2 allies. 

Do you have more info about it ? i doubt this is the answer because i don't have all the information but if trouble was brewing in a clinic maybe it was an argument as to which clinic was better or smth of that nature