A staircase is a circulation node, a vertical link between different levels, a space-defining structure and the only element of a building that is, by virtue of its function, essentially three-dimensional. As such, a staircase is a piece of architecture in its own right.
Staircases are a measure of the technical development and the cultural, social and political status of a society. Originally a mere aid to overcoming differences of level, they were developed into monumental structures that elevated the temples and palaces of ancient Greece and Rome, demonstrating the social and political hegemony of these cultures. In the Middle Ages, staircases were often housed in separate towers, and it was only during the Renaissance that they were reintegrated into the layout of buildings as dominant spatial elements.
Today, a staircase may fulfil a purely functional role, as an escape route, for example; but it may also be an imposing element that testifies to the status of a building or its client.