Just like the Staatsoper, many people threw back their heads and howled when the Haas Haus was finished in A.D. 1990. Designed by Hans Hollein, the building seems to be everything Vienna is not. There is glass, there is concrete, there are – gasp! – square windows.

But Hollein had an older Vienna in mind. The Haas Haus stands at the south corner of Vindobona, the city’s ancient Roman castrum, and its facade echoes the curved corners of fortress walls. Through the clever use of glass, the Gothic Stephansdom and the 19th century Kärntner Strasse are also brought into its orbit. 1,000 years of history are tied up in a modernist bow.