The lecture Impromptu by Catherine Mosbach, one of the most interesting landscape architects of our time, is a report from construction side. Instead of talking about finished projects such as her precious botanical garden in Bordeaux, she talks about projects, which are currently under construction.

Her reports from construction sites such as the landscaping of the Louvre in Lense or the Taichung Gateway park are accompanied by execution drawings, images of large concrete formwork full of armouring steel followed by images of mounds formed by excavated soil. The detailed descriptions of the construction process are accompanied by reflections on the connection between the very small and the very large or on the hidden infrastructure underneath todays large-scale landscape projects. There are cyanobacteria, a topography designed to be subject to torrential rain, waterbeds, a wall of moss and much more.

In addition, Catherine Mosbach also talks about the challenges of realizing her works, about technological and climatic challenges, administrative and political challenges and about how she reacted to them, she explains what worked and what did not work at all.

Last but not least Impromptu is also a story about how one project after the other a certain kind of visual grammar can develop, be refined and complemented by new forms and geometries. Indeed, architecture is a means of constructing effects and when the effect one aims at is clear an appropriate geometry can be invented.