Venice in Vienna was a walkable theatre stage, scripted architecture and a total artwork, at the same time. Temporary in its structure, volatile in its use and as the imitation of old Venice a symbol of decay, Venice in Vienna can be seen as an allegory of the ephemeral. By introducing the amusement park of Vienna's Fin de siècle as an exemplary work of architecture, conclusions about the significance of the ephemeral in architecture at the time of early modernism can be drawn. Venice in Vienna represents modernity in its programmatic as well as in its transitory sense. The notion of the ephemeral is typically discussed in categories, such as art, theatre and entertainment and less likely in the architectural discourse. However, especially in times of renewal the ephemeral could imply the opportunity of change. Abstraction in art, atonality in music and scientific breakthrough were the achievements of modernity. While movement characterized art and science around the turn of the century, architecture remained classical. Topic and aim of this work is to show the connection between temporary structures in built space and the development of new architectural concepts in beginning modernism. The present study begins with the consideration of the ephemeral in its different architectonical manifestations, continues with the specification of staging in built space, and ends with the interpretation of the ephemeral in architecture based on the description of the amusement city in its manifold ambiguity. Against the backdrop of renewal and awakening Venice in Vienna shows the ephemeral in architecture as a playground of modernity.