Part of the city’s defensive complex, the glacis was an open area in front of the city walls that was originally intended to ensure free lines of fire. Beyond it lay the suburbs. In 1770 Joseph II had it levelled, trees planted and paths laid out. By the nineteenth century the fortifications had lost their protective and defensive function. Until it was built over during the course of the construction of the Ringstrasse, the glacis was a popular place of recreation for the Viennese citizenry.