Spodek

In the 1960s, when the United States and USSR were racing to send humans to space, the attention of people all around the world was trained on the skies. It was during this time that Poland brought outer space to its own city of Katowice. Or more specifically, a UFO. 

The growing industrial hub of Katowice, the largest city of the rich region of Upper Silesia, was in need of a dome arena for sporting and cultural events. So came the Spodek, the Polish word for "saucer." Construction started in 1964 and was quickly stopped for 18 months because many people suspected the innovative and unusual design was not structurally stable. It resumed in 1966 and the complex was ready in 1971. 

The construction of Spodek was hidden from the Polish government. Jerzy Ziętek, a legendary regional leader, was supposed to build a new housing estate for miners and instead invested in this shocking project. When Wiesław Gomułka, a Polish communist leader, visited Katowice, his visit was carefully planned so he won't have to drive by the construction site. The initial cost projection of PLN 200 million quadrupled. 

When it was finally completed, the venue bore an undeniable resemblance to an alien spaceship, and the odd shape helped make the saucer an icon of the city and even country. Up until the early 2000s, Spodek was the largest indoor arena in Poland, holding over 11,000 people. It has since been surpassed by newer and bigger complexes, but is still regarded as the most iconic building of 1960s Poland, and most every Polish citizen knows its UFO-like shape very well.