History of Roof-Top Design
In today’s increasing problems of urbanization, over-population and global warming; the roof has become a new territory to be considered for potential development. In fact, throughout mankind’s history, roof-tops have been utilized for various purposes. This origin of these practice can be traced back 2,500 years to the Babylonians who constructed the magnificent ‘Hanging Gardens of Babylon’, the first ever roof garden known to have been built on top of a building.
The development of this ancient concept whereby roof-tops of buildings are exploited to provide landscaping and open spaces has been widely practiced in recent years. The once neglected space of the building is now playing a vital role in providing solutions for densely populated urban centers around the world.
In ancient times, roof-top design took the form of terracing with multiple layers of horizontal spaces stacked on top of one another. The earliest terraces can be traced back to an ancient cylinder seal found in Susa (now Iran) which represented a tower. Dated 5,000 B.C., this seal depicts an image of a temple on a high terrace.
The image shown in this seal became inspiration to the great ziggurat or ‘temple towers’ of ancient Mesopotamia. These sun-dried brick towers built from around 2,200 to 500 B.C. were a series of stepped terraces with a temple or altar at its summit. Today, the best preserved ziggurat that is still exist is the Ziggurat of Ur, an ancient Sumerian City. However, the more widely known pyramidal artificial mountain has to be the biblical Tower of Babel or Ziggurat of Etemenanki, ‘the house that is the foundation of heaven and earth.’ The Tower of Babel was a series of seven terraces, each of a different color related to the spheres of the seven planets.
While excavating the ruins of a ziggurat in the early 1920’s, the renowned English archaeologist Sir Leonard Wooley discovered evidence that large trees had been planted on the 3 upper terraces of the towers. However, the ziggurat plantings were now true roof gardens as these towers had solid cores of rubble and soil which made extensive landscaping impractical. The first true roof-top garden did not appear until 1,500 years later when the great King Nebuchadnezzar built the Hanging Gardens of Babylon on the roof of an iconic building in the south citadel of his capital city. This was the first genuine roof garden known to have been constructed on top of an occupied building with its terraces estimated to have been 75 feet above ground. Legend has it that these gardens were built by Nebuchadnezzar to please his Median wife from the hill country who wept for the green mountains of her native land. Due to the fact that the gardens covered a wide 3 acres land, there was a need for great structural support for the weight of heavy soil layers and other elements required for an elevated garden. Hence, Nebuchadnezzar gave orders to build the first stone building with barrel vaults as support for the hanging garden.
The garden was like a stadium with stepped-back terraces supported by 2 tiers of seven barrel vaults. The pillars of the vaults were 4 feet thick and the external wall was 22 feet thick. The roof was flat with a white marble balustrade 50 feet high which bore colossal statues of all the kings and great men of the empire. The roof was composed of 2 rows of bricks covered from end to end with a thick layer of lead for waterproofing. On top of it was a layer of soil 12 feet thick in which olive trees, palms, clove trees and cinnamon bushes were planted. Since the pillars were made of sun-dried bricks and soil; trees planted on the terraces were able to having their roots penetrating the pillars to reach the earth below. The Royal Chambers were located under the terraces much like a series of rooms facing the roof gardens in today’s high-rise apartment houses. Water for the plants was drawn up from the Euphrates River by a device in which pulleys drew a continuous belt with attached buckets from the well shaft to the garden above.