Click on title to view photo in large format. The view down Graben Street in Vienna, Austria. This avenue dates back to an old Roman settlement, when it was a trench running in front of the medieval city walls. During the 12th century, the trench was filled in and became one of the city’s first residential streets. Over the centuries Graben Street has been the main market street as well as the location for most major craftsmen. By the late 18th century, however, the avenue had emerged as the city’s most prestigious address. Graben Street became Vienna’s first pedestrian zone in 1974. Today, it not only is home to some of the most luxurious retail shops in the city, it often hosts major art installations like the geometric panels shown in the photo.