Check out the Palace of Culture and Science
Other than medieval architecture, Warsaw is also known to have some really interesting Brutalist architecture and one of the most prominent ones is the Palace of Culture and Science, a 237 meters high-rise building regarded as the second tallest building in the city, second only to Varso. The high-rise was built in 1955 and it is a great example of the utilitarian nature of Brutalism designs and constructions so prevalent in Europe during that time.
You would probably notice the similarity between this building and those in Moscow if you had already been there. It is a common Soviet architectural design for high-rise buildings, and you can see examples of it all throughout the former Soviet satellite states. You may visit Warsaw with the Communist Warsaw History Tour while riding the communist-vintage Nysa 522 minivan, which is the best way to find out about the city's many other brutalist architectures from the Soviet era.