Otto Wagner

The Steinhof complex where Am Spiegelgrund was has a long history dating all the way back to 1908, a history that in many ways predates the Spiegelgrund killings. When most people think of Steinhof, the first thing that appears in their minds is not the site where the Spiegelgrund killings took place. Rather, the first thing that will come to their minds is the Kirche Am Steinhof, a massive and beautiful church built by Otto Wagner at the Steinhof Complex. The Steinhof complex that would later be the location of the Am Spiegelgrund clinic has lots of instances of what we'd call Jugendstil architecture, in which architecture does not exist for its own sake, but rather, it has a function of some sorts.

This can be seen at the Jugendstil Theater, where the Spiegelgrund Memorial is in front of. It can also be seen in the architecture of the Otto Wagner Hospital. 

You can also see traces of him all over the U-Bahn as well, as best exemplified by the Karlsplatz Station.