Some buildings are meeting places. A large number of people can gather at a temple or theater or stadium to worship god or to hear or see what other people say or do. In Christendom they are called churches. Until we began to build skyscrapers, religious buildings were usually the largest, tallest buildings in a town. Fortresses and castles were also big but usually were not in town. Big buildings require much work to make, thus can symbolize power. They impress and they give a focus to cities.