Plattenbau is a type of apartment building that was popular in some parts of Europe in the 1950s and 1960s. They are large buildings made from large, square prefabricated concrete panels, so they look like they are made up of lots of big, square blocks. They can be tall, with lots of floors, or short. Plattenbau buildings were often built quickly and cheaply to provide a lot of homes to people in a short amount of time.