You're looking at a memorial for the second world war. This is one too. And this. They look different from other memorials. They don't show flags, heroes or victims. These abstract shapes and geometric forms seem to come from another planet. The communist party that built these monuments no longer exists. In fact, the country they're in no longer exists. Why do these monuments look so weird? Why were many abandoned and some even destroyed? Monuments sometimes seem invisible. Do you really know who the local man on the horse is? But monuments matter. They show us our values. And how values can change. The second world war was the greatest conflict of all time. Most define how we should remember this war. The battle for Stalingrad in the Soviet Union cost more lives than the entire English and American losses combined. On the last day of September, Hitler announced that the fall of the city was only a matter of a few days. When the memorial park to this battle opened, this was the biggest statue in the world. It's mother Russia pointing the way with open mouth and a big sword. It shows the power of the unified nation. To the west in Germany, the message of another mother is different. This time she is not victorious but grieving over the loss of her son. Warning for the tragedy of the loss of life war brings. In America, this world war two memorial shows their identity as victors. The atmosphere is uplifting. People take pictures of their home state. But in the former socialist state of Yugoslavia, world war two memorials look completely different. I traveled all across the western Balkans to show you these amazing structures and tell their story. This is Tjentiste. In a field, two roads lead to two concrete shapes. If you pass the monument, you can see it resembles wings. A sign resembling victory. Shapes in the stone show abstract faces. This place was the location of a brave escape. In the second world war many people resisted the Axis forces. But the most successful resistance group could be found in the western Balkans. In this valley in 1943, Tito and 22.000 partisans were surrounded by 127.000 Axis forces. They made an unbelievable escape but lost many soldiers. This monument remembers the fallen. It's an amazing work of art. But its design tells a geopolitical story. The war in Yugoslavia was very bloody. An estimated 6 to 11 percent of the population died. That's almost as much as the Soviet Union. So after the war, countless families needed to remember their dead. But the first memorials don't look like the later abstract versions. They're just simple slabs. This is because just after the war it was local communities that made simple memorials. But even the bigger ones built by the state don't look abstract at all. Why is this? The Yugoslav Communist Party looked up to the Soviet Union as a big brother. So they follow the Soviet style of socialist realism. A style idolizing the life of the people. I mean, look at these veins. But they soon find out that big brother is also a big bully. They distance themselves from the Soviets. So instead of showing workers that never skip leg day, they take inspiration from Western art forms and develop their own style. You get abstract monuments, organic shapes. These have become known as Spomenik in the West after the Serbo-Croat for monument. But the split with the Soviets is not the only reason why they look so different. Yugoslavia had a problem. World War II in Yugoslavia was not a simple story of partisan winners and German losers. The Yugoslav state was full of different ethnicities and different religions. During the Axis invasion, many clashed in a bloody civil war. Nazi Germany installed a puppet regime in Yugoslavia. This concrete flower is a monument at Jasenovac, Croatia's Auschwitz. The Croatian fascist Ustasa killed an estimated 83,000 Serbs, Jews and Roma in this death camp and many more outside. But after the war, former enemies now have to live together. The partisans want to forget this divisive past and look to the future. A revolutionary socialist future where ethnic and religious identities are not important. So when a first design for a memorial focused on the suffering of victims, the leader Tito was afraid this would stoke ethnic tensions. So instead he chose this flower, a symbol of life, rebirth and forgiveness. The communist party used monuments to create an official interpretation of the past in order to gain control of its society in the given present. It is not just the party though. Many monuments were initiated by local communities. Instead of religious symbols, you get monuments that celebrate the socialist revolution. This is the Kosmai monument. It can be interpreted as a five-pointed star, the same star you can find in the Yugoslav flag, resembling the five fingers of the worker's hand. This monument is to the Kosmai partisans that were fighting the Germans. If you look closer, you see that the structure has five individual points, as if gravity does not exist. This sculpture looks futuristic. It almost looks ready to take off. This is not by coincidence. Yugoslav society was an optimistic society focused on the future. But this future would only be real if new generations learned about socialist ideology. So the monuments also become teaching grounds. This monument in Croatia became one of the most important memorial places. Around three million people came to visit. And this is still just one of an estimated 20 to 40 thousand monuments to the second world war. But in the end, the monuments did not succeed in their goal. This is the Petrova Gora monument in Croatia. It has been erected to remember the execution of thousands of Serbian peasants. It is now completely abandoned. Looters took many aluminium plates. A radio antenna now sits on the structure. This once proud monument is literally a shell of itself. But other monuments have suffered an even worse fate. This is the Makljen monument in Bosnia Herzegovina. Unknown people destroyed it with dynamite. It's just one of many that did not survive. Why were these monuments demolished? In the beginning of the 1990s Yugoslavia came to a violent end. I made a video that covers this topic. The nation broke apart and the fragments that emerged quickly needed to decide what their own story was. For some that meant a total break with everything that Yugoslavia stood for. Destroying the monuments that were once meant to unite. In other places, monuments were more easily reimagined to fit into the new national identity. But this history was completely ignored when the West discovered these structures. Their alien looks are great for dystopian fantasies. They can be found in artwork, in games, set pieces in Netflix series. But by focusing on their looks alone you lose important context. This leads to some interesting use cases. The Croatian Auschwitz becomes a petty backdrop to promote sunglasses. Monuments to massacres are perfect for parkour. And although the appeal of these places is understandable, they are important memorials made to remember thousands of casualties and with a specific socialist goal in mind. They rejected the Soviet example and made their own unique style, in what is arguably the biggest public art project in the world. With the goal to shape different ethnicities into one Yugoslav people. A goal that ultimately failed. Knowing that context makes them all the more interesting. The people designing these memorials were really artistic. But to make their dreams a reality, they needed to know math. As a historian I love words but I'm scared by equations. 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