The Hanging Gardens of Babylon, one of the Seven Wonders of the Ancient World, is the only one whose location has not been definitively established.
The Hanging Gardens were described as a remarkable feat of engineering: an ascending series of tiered gardens containing all manner of trees, shrubs, and vines. The gardens were said to have looked like a large green mountain constructed of mud bricks.
Traditionally they were said to have been built in the ancient city of Babylon, near present-day Hillah, Babil province, in Iraq. The Babylonian priest Berossus, writing in about 290 BC and quoted later by Josephus, attributed the gardens to the Neo-Babylonian king Nebuchadnezzar II, who ruled between 605 and 562 BC. There are no extant Babylonian texts which mention the gardens, and no definitive archaeological evidence has been found in Babylon.
According to one legend, Nebuchadnezzar II built the Hanging Gardens for his Median wife, Queen Amytis, because she missed the green hills and valleys of her homeland. He also built a grand palace that came to be known as "The Marvel of the Mankind".
Because no physical evidence for the Hanging Gardens has been found at Babylon, it has been suggested that they were purely mythical, and the descriptions found in ancient Greek and Roman writers including Strabo, Diodorus Siculus and Quintus Curtius Rufus represent a romantic ideal of an eastern garden. If it did indeed exist, it was destroyed sometime after the first century AD.
Stephanie Dalley suggests that the original garden may have been a well-documented one that the Assyrian king Sennacherib (704–681 BC) built in his capital city of Nineveh on the River Tigris, near the modern city of Mosul.
There are five principal writers whose descriptions of Babylon are extant in some form today. These writers concern themselves with the size of the Hanging Gardens, their overall design and means of irrigation, and why they were built.
Josephus (c.37–100 AD) quotes a description of the gardens by Berossus, a Babylonian priest of Marduk writing circa 290 BC. Berossus described the reign of Nebuchadnezzar II, and is the only source to credit that king with the construction of the Hanging Gardens.
In this palace he erected very high walks, supported by stone pillars; and by planting what was called a pensile paradise, and replenishing it with all sorts of trees, he rendered the prospect an exact resemblance of a mountainous country. This he did to gratify his queen, because she had been brought up in Media, and was fond of a mountainous situation.
For his description of the gardens, Diodorus Siculus (active c.60–30 BC) seems to have consulted the 4th century BC texts of both Cleitarchus (a historian of Alexander the Great) and Ctesias of Cnidus. Diodorus ascribes the construction to a Syrian king.
The park extended four plethra on each side, and since the approach to the garden sloped like a hillside and the several parts of the structure rose from one another tier on tier, the appearance of the whole resembled that of a theatre. When the ascending terraces had been built, there had been constructed beneath them galleries which carried the entire weight of the planted garden and rose little by little one above the other along the approach; and the uppermost gallery, which was fifty cubits high, bore the highest surface of the park, which was made level with the circuit wall of the battlements of the city. Furthermore, the walls, which had been constructed at great expense, were twenty-two feet thick, while the passageway between each two walls was ten feet wide. The roof above these beams had first a layer of reeds laid in great quantities of bitumen, over this two courses of baked brick bonded by cement, and as a third layer of covering of lead, to the end that the moisture from the soil might not penetrate beneath. On all this again earth had been piled to a depth sufficient for the roots of the largest trees; and the ground, when levelled off, was thickly planted with trees of every kind that, by their great size or other charm, could give pleasure to the beholder. And since the galleries, each projecting beyond another, all received the light, they contained many royal lodgings of every description; and there was one gallery which contained openings leading from the topmost surface and machines for supplying the gardens with water, the machines raising the water in great abundance from the river, although no one outside could see it being done. Now this park, as I have said, was a later construction.
The next account is from Quintus Curtius Rufus (active 1st century AD), who probably drew on the same sources as Diodorus.
The Babylonians also have a citadel twenty stades in circumference. The foundations of its turrets are sunk thirty feet into the ground and the fortifications rise eighty feet above it at the highest point. On its summit are the hanging gardens, a wonder celebrated by the fables of the Greeks. They are as high as the top of the walls and owe their charm to the shade of many tall trees. The columns supporting the whole edifice are built of rock, and on top of them is a flat surface of squared stones strong enough to bear the deep layer of earth placed upon it and the water used for irrigating it. So stout are the trees the structure supports that their trunks are eight cubits thick and their height as much as fifty feet; they bear fruit as abundantly as if they were growing in their natural environment. And although time with its gradual decaying processes is as destructive to nature's works as to man's, even so this edifice survives undamaged, despite being subjected to the pressure of so many tree-roots and the strain of bearing the weight of such a huge forest. It has a substructure of walls twenty feet thick at eleven foot intervals, so that from a distance one has the impression of woods overhanging their native mountains. Tradition has it that it is the work of a Syrian king who ruled from Babylon. He built it out of love for his wife who missed the woods and forests in this flat country and persuaded her husband to imitate nature's beauty with a structure of this kind.
Strabo (c.64 BC – 21 AD) described the Hanging Gardens as follows, in a passage thought to be based on the lost account of Onesicritus from the 4th century BC:
Babylon, too, lies in a plain; and the circuit of its wall is three hundred and eighty-five stadia. The thickness of its wall is thirty-two feet; the height thereof between the towers is fifty cubits; that of the towers is sixty cubits; and the passage on top of the wall is such that four-horse chariots can easily pass one another; and it is on this account that this and the hanging garden are called one of the Seven Wonders of the World. The garden is quadrangular in shape, and each side is four plethra in length. It consists of arched vaults, which are situated, one after another, on checkered, cube-like foundations. The checkered foundations, which are hollowed out, are covered so deep with earth that they admit of the largest of trees, having been constructed of baked brick and asphalt – the foundations themselves and the vaults and the arches. The ascent to the uppermost terrace-roofs is made by a stairway; and alongside these stairs there were screws, through which the water was continually conducted up into the garden from the Euphrates by those appointed for this purpose, for the river, a stadium in width, flows through the middle of the city; and the garden is on the bank of the river.
Philo of Byzantium (4th–5th century AD) is the last of the classical sources. The description of the gardens in his A Handbook to the Seven Wonders of the World is thought to be independent of earlier Greek sources. The method of raising water by screw matches that described by Strabo.
The so-called Hanging Gardens have plants above ground, and are cultivated in the air, with the roots of the trees above the (normal) tilled earth, forming a roof. Four stone columns are set beneath, so that the entire space through the carved pillars is beneath the (artificial) ground. Palm trees lie in place on top of the pillars, alongside each other as (cross-) beams, leaving very little space in between. This timber does not rot, unlike others; when it is soaked and put under pressure it swells up and nourishes the growth from roots, since it incorporates into its own interstices what is planted with it from outside. Much deep soil is piled on, and then broad-leaved and especially garden trees of many varieties are planted, and all kind of flowering plants, everything, in short, that is most joyous and pleasurable to the onlooker. The place is cultivated as if it were (normal) tilled earth, and the growth of new shoots has to be pruned almost as much as on normal land. This (artificial) arable land is above the heads of those who stroll along through the pillars. When the uppermost surface is walked on, the earth on the roofing stays firm and undisturbed just like a (normal) place with deep soil. Aqueducts contain water running from higher places; partly they allow the flow to run straight downhill, and partly they force it up, running backwards, by means of a screw; through mechanical pressure they force it round and round the spirals of the machines. Being discharged into close-packed, large cisterns, altogether they irrigate the whole garden, inebriating the roots of the plants to their depths, and maintaining the wet arable land, so that it is just like an evergreen meadow, and the leaves of the trees, on the tender new growth, feed upon dew and have a wind-swept appearance. For the roots, suffering no thirst, sprout anew, benefitting from the moisture of the water that runs past, flowing at random, interweaving along the lower ground to the collecting point, and reliably protects the growing of trees that have become established. Exuberant and fit for a king is the ingenuity, and most of all, forced, because the cultivator's hard work is hanging over the heads of the spectators.
There is some controversy as to whether the Hanging Gardens were an actual construction or a poetic creation, owing to the lack of documentation in contemporaneous Babylonian sources. There is also no mention of Nebuchadnezzar's wife Amyitis (or any other wives), although a political marriage to a Median or Persian would not have been unusual. Many records exist of Nebuchadnezzar's works, yet his long and complete inscriptions do not mention any garden.
Herodotus, who describes Babylon in his Histories, does not mention the Hanging Gardens.
To date, no archaeological evidence has been found at Babylon for the Hanging Gardens. It is possible that evidence exists beneath the Euphrates, which cannot be excavated safely at present. The river flowed east of its current position during the time of Nebuchadnezzar II, and little is known about the western portion of Babylon. Rollinger has suggested that Berossus attributed the Gardens to Nebuchadnezzar for political reasons, and that he had adopted the legend from elsewhere.
A recent theory proposes that the Hanging Gardens of Babylon were actually constructed by the Assyrian king Sennacherib (reigned 704 – 681 BC) for his palace at Nineveh. Stephanie Dalley posits that during the intervening centuries the two sites became confused, and the extensive gardens at Sennacherib's palace were attributed to Nebuchadnezzar II's Babylon. Recently discovered evidence includes excavation of a vast system of aqueducts inscribed to Sennacherib, which Dalley proposes were part of a 80-kilometre (50 mi) series of canals, dams, aqueducts, used to carry water to Nineveh with water-raising screws used to raise it to the upper levels of the gardens.
Dalley bases her arguments on recent developments in the decipherment of contemporary Akkadian inscriptions. Her main points are:The name "Babylon", meaning "Gate of the Gods" was applied to several Mesopotamian cities. Sennacherib renamed the city gates of Nineveh after gods, which suggests that he wished his city to be considered "a Babylon".
Only Josephus names Nebuchadnezzar as the king who built the gardens, but although Nebuchadnezzar left many inscriptions none mentions any garden or engineering works. Diodorus Siculus and Quintus Curtius Rufus specify a "Syrian" king.
By contrast Sennacherib left written descriptions and there is archaeological evidence of his water engineering. His grandson Assurbanipal pictured the mature garden on a sculptured wall panel in his palace.
Sennacherib called his new palace and garden "a wonder for all peoples". He describes the making and operation of screws to raise water in his garden.
The descriptions of the classical authors fit closely to these contemporary records. Before the Battle of Gaugamela in 331 BC Alexander the Great camped for four days near the aqueduct at Jerwan. The historians who travelled with him would have had ample time to investigate the enormous works around them, recording them in Greek. These first-hand accounts do not survive into our times, but were quoted by later Greek writers.
King Sennacherib's Hanging Garden was considered a World Wonder not just for its beauty – a year-round oasis of lush green in a dusty summer landscape – but also for the marvellous feats of water engineering that maintained the garden.
There was a tradition of Assyrian royal garden building. King Ashurnasirpal II (883–859 BC) describes what he had done:
I dug out a canal from the (river) Upper Zab, cutting through a mountain peak, and called it the Abundance Canal. I watered the meadows of the Tigris and planted orchards with all kinds of fruit trees in the vicinity. I planted seeds and plants that I had found in the countries through which I had marched and in the highlands which I had crossed: pines of different kinds, cypresses and junipers of different kinds, almonds, dates, ebony, rosewood, olive, oak, tamarisk, walnut, terebinth and ash, fir, pomegranate, pear, quince, fig, grapevine.... The canal water gushes from above into the garden; fragrance pervades the walkways, streams of water as numerous as the stars of heaven flow in the pleasure garden.... Like a squirrel I pick fruit in the garden of delights...
Sennacherib is the only Mesopotamian king who has left a record of his love for his wife – a key part of the romantic classical story:
And for Tashmetu-sharrat the palace woman, my beloved wife, whose features the Mistress of the Gods has made perfect above all other women, I had a palace of loveliness, delight and joy built...
Sennacherib's palace was comparable in size to Windsor Castle in England. He specifically mentions the massive limestone blocks that reinforce the flood defences. Parts of the palace were excavated by Austin Henry Layard in the mid-19th century. His citadel plan shows contours which would be consistent with Sennacherib's garden, but its position has not been confirmed. The area has been used as a military base in recent times, making it difficult to investigate further.
A sculptured wall panel of Assurbanipal shows the garden in its maturity. There is one original panel and the drawing of another in the British Museum, although neither is on public display. Several features mentioned by the classical authors are discernible on these contemporary images.
The irrigation of such a garden demanded an upgraded water supply to the city of Nineveh. The canals stretched over 50 km into the mountains. Sennacherib was proud of the technologies he had employed, and describes them in some detail on his inscriptions. For example:
At the headwater of Bavian (Khinnis) his inscription mentions automatic sluice gates but does not say how they worked:
The sluice gate of that canal opens without a spade or a shovel and lets the waters of abundance flow.: its sluice gate is not opened by the labour of men's hands, but by the will of the gods.
An enormous aqueduct crossing the valley at Jerwan was constructed of over 2 million dressed stones. It used stone arches and waterproof cement. On it is written:
Sennacherib king of the world king of Assyria. Over a great distance I had a watercourse directed to the environs of Nineveh, joining together the waters.... Over steep-sided valleys I spanned an aqueduct of white limestone blocks, I made those waters flow over it.
He claims to be the first to deploy a new casting technique in place of the "lost-wax" process for his monumental (30 tonne) bronze castings, and describes the making of his water screws (though once again he does not say exactly how they were driven):
Whereas in former times the kings my forefathers had created bronze statues imitating real-life forms to put on display inside temples, but in their method of work they had exhausted all the craftsmen, for lack of skill and failure to understand the principles they needed so much oil, wax and tallow for the work that they caused a shortage in their own countries – I Sennacherib, leader of all princes, knowledgeable in all kinds of work, took much advice and deep thought over doing that kind of work.... I created clay moulds as if by divine intelligence for cylinders and screws... In order to draw up water all day long, I had ropes, bronze wires and bronze chains made. And instead of a shaduf I set up the cylinders and screws of copper over cisterns....I raised the height of the surroundings of the palace, to be a Wonder for all Peoples... A high garden imitating the Amanus mountains I laid out next to it, with all kinds of aromatic plants, orchard fruit trees, trees that enrich not only mountain country but also Chaldea (Babylonia), as well as trees that bear wool, planted within it.
Sennacherib could bring the water into his garden at a high level because it was sourced from further up the mountains. He then raised the water even higher by deploying his new water screws. This meant he could build a garden that towered into the sky with large trees on the top of the terraces – a stunning artistic effect that surpassed those of his predecessors and which justifies his own claim to have built a "Wonder for all Peoples".