Spirits from the sky

Andrew Motion is overawed by Georg Gerster's bird's-eye views of ancient civilisations collected in The Past From Above

The Past From Above
photographs by Georg Gerster, edited by Charlotte Trumpler
416pp, Francis Lincoln, £50

Archaeologists took a great leap forward in understanding the past as soon as they were able to look at the Earth from the air: for the first time, they could map the overall design of ruinous sites, establish connections between apparently diverse details, and see the relationship between buildings and the natural environment. The first significant breakthrough was made in 1906 by PH Sharpe, who snapped Stonehenge from a war balloon during an exercise flight. By the late 1930s, and thanks to better cameras, let alone more reliable aircraft, Osbert Guy Crawford, who is generally described as the inventor of aerial photography in archaeology, had developed methods of producing and analysing the results which have stayed pretty much the same ever since. He realised that it was sensible to work at times of day when the angle of sunlight showed other-wise hidden elements, he was able to understand the patterns created by lighter and darker patches of vegetation, and he began to reconstruct ancient farming systems as well as town-scapes. "Aerial photography," he said in 1938, "has provided archaeology with a research tool that is as valuable to it as the telescope was for astronomy."

For the last 40-odd years, Georg Gerster has followed where Crawford led, building on his example and learning from other pioneers such as George Allen, Antoine Poidebard and George Johnson. In The Past From Above he has selected 250 photographs from his enormous repertoire, arranging them in groups ("Culture and Nature", "Villages and Towns", "Frontier Walls" and so on) and enlisting various experts to provide short commentaries on each picture. Specialists will find their own particular rewards, but generally interested parties will be captivated as well. The images - many taken in very difficult circumstances - are fascinating in their details and often intensely beautiful in their overall effect. And because the pictures can't help but play tricks with perspective, give mass an odd sense of weightlessness, and complicate the sense of relative scales, they often have a weirdly dream-like quality. If Kubla Khan had a library in Xanadu, he'd have kept this book on permanent display.

Whereas Crawford concentrated on local sites, Gerster takes on the world. His pictures of well-known English landmarks form only a small part of the collection, and although these have a striking freshness (Maiden Castle in Dorset, with the shadowed rings of the fort surrounded by the painterly abstractions of field-shapes), the real treasures of the book are photographs of far-flung places. The best of these are made to seem doubly precious because war and politics have made them inaccessible. The second/third-century World Heritage Site at Hatra in Iraq, for instance, where the ancient city appears as a huge ring of sandy blisters, centred on a fortified middle square. Or the seventh-century Median capital at Hamadan in Iran, where the white-and-grey houses flicker inside the spokes and rim of a gigantic wall-wheel. Or the immense hilltop fortress at Aleppo in Syria, where the worn gold of the defences seems to trickle down into the modern city that surrounds it. Although these images clarify our sense of what is real, they also create a feeling of entrancement - even of awe.

And then there are the monuments that appear to have been built for aerial viewing hundreds of years before aeroplanes were invented. The supple thrashing whale on the Pampa de Nasca in Peru, the spectral, almost-alien Giant at Blythe in California, or the even more vestigial figure at Cerro Unita in Chile, who holds open his saucer-eyes, and raises his right arm in a gesture which might just as well be forbidding as welcoming. It's impossible not to be magnetised by these images even as we are baffled by them. Because their functions are forgotten or only partially known, they have entered a new kind of existence and found a new kind of purpose: they commemorate the mystery of existence itself.

Part of that mystery stems from the fact that sites separated by colossal distances and cultural differences often have principles in common. This can no doubt be explained partly by practical requirements: cities needed walls, wherever on earth they were built. But there are smaller-scale similarities, too. The lovely umber U-shape of the Piazza Navona in Rome finds an unexpected echo in the much more primitive - but still astonishing - ball court in the Wupatki Pueblo in Arizona. The labyrinth on Blå Jungfrun in Sweden, which lies on a slab of bare rock like a flung-down necklace, recalls the grass labyrinth at Saffron Walden in Essex - where the softness of the grassy setting gives a more gentle and sophisticated impression. The ziggurat at Choga Zanbil in Iran, enclosing its square of weathered rock, develops the almost-smooth stump of the Tower of Babel.

Judging from the tone of his prose, and especially from the essay on the rock temples at Abu Simbel which closes the book, Gerster is a pragmatist, used to arguing his way through tense political situations. But the strange and suggestive pairings that he allows are proof that he is completely alive to the poetry of his subjects. Not that such proof is necessary. Every single photograph in this book combines scholarly interest with a sense of the numinous; it's the record of a valuable and oddly heroic life, as well as a thing of beauty.

&middot Andrew Motion is the poet laureate.

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