During a short trip to Europe, I visited Berlin and tried to soak up as much as I could in such a diverse city. A building that took my fancy was the Reichstag building (pictured above from inside the dome).
The original building goes as far back as 1894 and has endured a lot, including fires and multiple periods of war. Throughout these periods it served a variety of purposes but now houses the German Parliament. The dome was built in 1999 and provides a fantastic 360 view of the widespread city.
It is an amazing building and a must visit if you ask me. Although admission is free, you MUST register in advance and pass all the security checks including providing your passport. Information can be found at https://www.bundestag.de/en/visittheBundestag/dome/registration/245686