Buzludzha Monument

The Monument House of the Bulgarian Communist Party, also known as the Buzludzha Monument (), was built on Buzludzha Peak in central Bulgaria by the Bulgarian communist government and inaugurated in 1981. It commemorated the events of 1891, when a group of socialists led by Dimitar Blagoev assembled secretly in the area to form an organized socialist movement that led to the founding of the Bulgarian Social Democratic Party, a forerunner of the Bulgarian Communist Party.

Source: Wikipedia