I saw the painting shortly after seeing the original of the original, that is Pompeii itself. I went in the wake of last November's collapse of the House of Gladiators amid a torrent of abuse at Italy's inability to look after its ancient sites. The idea of a 2,000-year-old structure in one of Europe's most sensational remains being so neglected as to fall down, while money to save it had allegedly been siphoned off by the mafia, was astonishing.
As many scholars were quick to point out, much of the furore was rubbish. The house had nothing obviously to do with gladiators, but the media needed to get Russell Crowe into the story. Nor could the British complain. The Pompeiian building and its frescoes had been largely destroyed when the RAF bombed the site in 1943, as part of its casual assault on European civilisation. The building was a subsequent reconstruction and the collapse was of a reinforced concrete beam dislodged by movement in an unexcavated part of the site.
The spectacle of Pompeii at present is heartbreaking, a maze of barriers, scaffolding props, no-entry signs and temporary roofs, a monument to the unknown health and safety inspector. But two centuries of discovery, looting, rescuing, rebuilding, decaying and corruption are an object lesson not just in Italian public administration but in conservation ideology. Despite the valiant efforts of some 20 world universities to salvage Pompeii – or at least to travel the world talking about it – the fact is that most of what is visible today is the result of reconstruction. Any building left exposed to the elements without a roof soon collapses. The partial re-roofing of Pompeii – like the Victorian salvage of England's medieval churches – saved it from disintegrating into the earth from which it came.
What Pompeii presents is thus the ruin of a reconstruction of a ruin, an intellectual nonsense. The visitor sees 20th-century concrete and steel rusting and collapsing. A re-erected column in the House of the Faun looks fit to fall again and is propped by scaffolding. Replicas abound. Ugly temporary roofs are jammed on top of courtyards, stripping them of ancient atmosphere or modern purpose. Only the streets seem fit for purpose.
Up the coast at Herculaneum is a contrast. Under the generosity of the Packard Institute, its smaller scale, tightly packed streets are emerging from beneath its urban surroundings in a vivid evocation of a seaside Roman town. Seen from above, a carpet of 21st-century replica roofs are enabling houses, courtyards, baths and shops to take on their old form, not like the gaping, degenerating shells of Pompeii.
Again, Herculaneum is largely a reconstruction, mostly at the hands of the great Italian archaeologist, Amedeo Maiuri, in the first half of the last century. As Andrew Wallace-Hadrill, doyen of Herculaneum studies, has written of the place, "What we see is not an ancient town as preserved by an eruption, but fragments painstakingly pieced together, stabilised, reinforced, restored," in effect a "re-presentation". He calls the celebrated House of the Telephus Relief "a skilful composite, true to the spirit of the original but not actually archaeological evidence of what was". Nothing is more delightful than the apparently extant "room of the little weaving girl", with its fragment of a child's corpse caught in the moment of death on its upstairs bed. This was a tableau entirely fabricated by Maiuri, yet it has become the folklore of Herculaneum.
As Wallace-Hadrill remarks, "the changing ideological priorities of each age" would today dictate the site be left a stabilised shell. But at least Maiuri re-roofed many of the houses, put in drains and conserved the city. The ghosts of ancient Rome walk the streets of Herculaneum more vividly than they do Pompeii.
At a conference on Pompeii organised by Cambridge's Mary Beard last July, speaker after speaker seemed to agree that the best bet for Pompeii, and sites like it, was probably to come clean, to give visitors some approximation of what these ancient places were like and how they worked. Since it is impossible to stabilise a ruin of a ruin, other than with stupefying amounts of concrete, the better part of wisdom is to put the houses back into long-term conservable order. That could mean Pompeii – or parts of it – as it was at the time of its destruction. Clearly the old must be distinguishable from the new and every effort made to respect authenticity. But a part-reconstruction must make more sense than the seminars, backbiting, politicking and inertia that now fiddle while Pompeii decays.
The worm is turning on the 20th-century maxim that everything old should be "conserved as found". This was understandable in a century when the losses of war and vandalism could be stemmed only by a fundamentalist aversion to reconstruction. But as long ago as 1987, the National Trust rebuilt Uppark House in Sussex after its destruction by fire. English Heritage has recreated the Norman interior of Dover Castle. At St Fagan's outside Cardiff, the late medieval church of St Teilo has been brightly repainted and refurnished as it would have been before the Reformation. Meaning is creeping back into conservation.
This brings us back to the Martin painting. To have left it a ruin might have enthralled art historians, but it would have been unexhibitable and indeed meaningless to most viewers. The same goes for such Roman remains as the villas at Lullingstone and Fishbourne, where bits of restored wall, fragments of tessellated pavement and ghosts of mosaics lie stripped of context and atmosphere under the swimming-pool sheds of 20th-century archaeological fashion. They are frigid.
The tragedy of Pompeii is not that what we see is not what the early discovers unearthed: that would soon have vanished. The tragedy is that the discoverers did not rebuild and thus preserve more thoroughly, so we might now see more of what they found. Nobody seriously regrets Sir Arthur Evans's rebuilding of Knossos in Crete, except that he should perhaps have gone further.
These arguments are controversial. No one wants to destroy fragments of past civilisations, but not destroying is only the start of the debate. Preservation is different from freezing ruins at some arbitrary moment in their decay. The cult of the ruin has its place. But seeking to reinterpret, even reconstruct, some works of the past no longer need attract jeers of "Disneyfication", and that too is preferable to terminal decay. If we can restore Martin's Pompeii we can surely restore Pompeii's.