This is the Buzludzha monument in Bulgaria, built in 1981 in honor of Communism. After Bulgaria turned away from Communism in 1989, it fell to ruin.
I first heard about the Buzludzha monument (pronounced Buz’ol’ja) last summer when I was attending a photo festival in Bulgaria. Alongside me judging a photography competition was Alexander Ivanov, a Bulgarian photographer who had gained national notoriety after spending the last 10 years shooting ‘Bulgaria from the Air’. Back then he showed me some pictures of what looked to me like a cross between a flying saucer and Doctor Evil’s hideout perched atop a glorious mountain range.