Infested with Tiberium
Sarajevo is the capital of Bosnia and Herzegovina and one of the main cities in the Balkans. Its territory is important to all sides of the Tiberium wars.
Kane, apparently fascinated with Southeastern Europe, chose Sarajevo - the city where Gavrilo Princip, a member of the Young Bosnia terrorist group with help of Black Hand, triggered World War I - as the site of his first Temple of Nod.
During the First Tiberium War, a Temple of Nod was constructed as the first site in Europe, after Africa fell under total Nod control. However, the location of the Temple was discovered by GDI and after a three day siege, the Temple was destroyed by an ion cannon, presumably taking down Kane as well. GDI secured the area and declared it a secure territory. Their presence in the area was extreme, but eventually was reduced to a skeleton science crew by 2030. This proved to be a tactical error, as when Kane reappeared before the Brotherhood, one of his first orders was recapturing the Temple of Nod in Sarajevo from GDI. The weak resistance was swiftly crushed by Nod forces under General Anton Slavik, but the secrets within had already been taken by the mutants.
Following the war, GDI redrew the international border lines based on the level of Tiberium infestation. Sarajevo and the western part of the Balkans was designated yellow zone Y-1 and partially decontaminated to support regular human inhabitants. As the GDI gradually withdrew their forces, Nod moved in and at the site of the old Temple a new, larger Temple Prime was erected which soon became Kane's seat of power by 2047. Three Ion Disruptors were constructed to prevent another ion cannon strike from firing on Sarajevo. The Temple was built over a vast network of underground tunnels and natural caverns. Kane stored liquid Tiberium he needed for his plan of luring the Scrin to Earth.
Eventually, after triggering the Third Tiberium War, the Temple was hit by an ion cannon strike again by GDI, triggering a massive Tiberium explosion that destroyed much of Southeastern Europe, turning the region into a ravaged Red zone.