History of Graben, Vienna
Though the name Graben literally means a "Ditch" or hole in the ground it is not since the middle ages that there has been a literal ditch here. Starting in the times of the Roman Empire there was a defensive Graben or ditch, somewhat like a Moat but without the water, around the Roman encampment of Vindobona.
Not until the 12th century was the ditch or Graben filled in, at which point it became flat land and a part of the important roads of the city with residential buildings around it, making this a fashionable new area of the city. However the large open space continued to be used as a marketplace up until the mid 18th century as was common in most european cities.
1295 - Earliest documented mentions of the Graben as a marketplace, in this case describing sale of fresh fruits.
1327 - Great Fire of Graben, a large fire destroys most buildings in the area
1455 - First fountain mentioned in the Graben, mainly as a ready source of water to fight fires
1564 - Butchers are moved out of the Graben due to complaints about the smells
1609 - Graben pictured by the artist Jacob Hoefnagel from Antwerp, better known for this engravings of animals under a magnifying lens
1733 - The current Peterskirche was completed after many years of construction, replacing the medieval structure
1753 - The daily Market stalls selling fresh food are removed, and 20 years later even the Christmas market is relocated as this becomes an increasingly upmarket residential area.
1781 - A young Wolfgang Motzart moves into a flat in the building in the building number today as "Graben 17", and which today is the small hotel Pension Nossek
1840 - Regularization of the increasingly chaotic buildings on the Graben starts a trend towards the clean open space you see today
1873 - Grabenhof completed replacing the Arkadenhof
1911 - Original Trattnerhof is replaced by the current two buildings so as to open the passage into old city
1970 - Peterskirche is transferred to the Opus Dei
1974 - The Graben becomes the first pedestrian area in Vienna