A Greek god exposed; ARCHITECTURE

Alexander Thomson Lighthouse, Glasgow

It was with a special architectural irony that the long-overdue retrospective of Alexander "Greek" Thomson opened for a sneak press preview last week. The exhibition, a model of respectful, intelligent curating, looked great, more than living up to the expectations of this key Glasgow 1999 show. But the building it is housed in - the Lighthouse, Scotland's new centre for architecture, design and the city - still needs some work. While the inside exhibition space is kitted out in Victorian splendour (rich red panels and the tinkling of light classical music), outside I like to think that Thomson, wherever he is now, is smiling down on this scene, if he has ever been able to forgive Glasgow for the way it treated his buildings and his reputation since his death in 1875. Unlike the city's other architect, Charles Rennie Mackintosh, Thomson - nicknamed "Greek" for his penchant for Grecian forms of abstract classicism - has been largely forgotten. Many buildings were demolished, leaving only one and a half of his extraordinary Presbyterian churches standing. Even these have not had a happy history. Caledonia Road Church, built by 1857, was gutted in an arson attack in 1965: vandals and a scrap merchant had already stripped the interior. After vigorous campaigning, the ruin was retained but now sits forlornly at a junction. His St Vincent Street Church at least made it to the World's Monuments Fund's list of 100 endangered buildings.

However, it's not the case, as the exhibition title suggests, that Thomson is entirely unknown in Glasgow. His churches, terraces and commercial buildings are part of the fabric of the city; they stop you dead in your tracks with their sublime appeal. But until now, little was known about Thomson, and this rightly ambitious show sets out to scotch a few myths and restore his reputation as a key figure in making Glasgow one of the great Victorian cities. The "Greek" tag earns a thorough going- over: not least because Thomson never left Britain, let alone visited Greece, and he was just as ready to use Gothic and Egyptian elements as Ionic columns.

Best of all are exhibits revealing the Thomson we never had chance to know because of demolition or unexecuted plans. A stunning model of Queens Park Church, hit by a bomb in 1943, dominates one room, with a computerised fly-through of the exotic-coloured interior. A video reconstruction of Thomson's plans for glass-roofed streets to replace city slums shows his involvement with public health: four of his children had died of cholera. There is much attention to interiors, too; his designs were just as audacious as his building plans, as we see in footage from the interior of Holmwood House (recently saved by the National Trust) and from one of his drawing-room sideboards. Forget every other sideboard you have encountered: this is monumental, like a building crossed with a hefty church organ.

Most fascinating are his recently rediscovered original drawings, including an astonishing design for the Albert Memorial. It's unclear why Thomson produced this image - he was not among architects invited to submit designs - but it's clear why it wasn't chosen. Like some Eastern temple, some hugely dramatic ancient Egyptian monument complete with lions at the base, it resembles a strange obelisk from a Goya-inspired apocalyptic dreamscape. Thomson loved obelisks, and said they embodied "an imperishable thought". It's inexplicable and sad that both Thomson's buildings and his reputation haven't fared likewise. But if any exhibition can redress the balance, this one can. At least, and not before time, Thomson will no longer be all Greek to us.

`Alexander Thomson: The Unknown Genius': The Lighthouse, Glasgow (0141 287 7346). Building opens 8 July. Exhibition closes 19 September