Constructed between 1911 and 1913, Centennial Hall in Wroclaw, Poland was designed by German architect Max Berg. Today, it's still a popular venue for concerts and sporting events, as well as a UNESCO World Heritage site.
The building, with its reinforced concrete cupola, was the largest of its kind anywhere when it was built. The dome is 23 meters high and the building can accommodate 7,000 people; even if you aren't attending a performance, it's worth visiting for the spectacular interior and cutting edge design.
It's easily reachable by bus and train and is located in Szczytnicki Park, one of Europe's oldest urban parks.