Plecnik, the genius of Prague

Anyone who visits the castle high up on its hill above the old city of Prague encounters "interventions" - porches, staircases, urns, obelisks, balustrades - which are clearly not medieval or baroque but which, in their resonant modernity and oddness, seem completely appropriate. These things date from the 1920s and were designed by Josip Plecnik, the architect who was asked by Tomas Masaryk, first president of the Republic of Czechoslovakia, to restore the castle as a symbol of independence and democracy. "It is possible to create a great historical monument of the Castle and its surroundings," Masaryk wrote to him in 1923, "and I cannot see anyone who would be able to carry out this historical task other than you." The result was an extraordinary triumph of architecture and landscape design.

Joze, or Josef, or Josip Plecnik is still less well known - at least in Britain - than some of his contemporaries. He was born in 1872, five years after Frank Lloyd Wright, four after Charles Rennie Mackintosh and three after Edwin Lutyens. And he was not a Czech but a Slovene - a fellow Slav - from the Austro-Hungarian town of Laibach, which is now called Ljubljana, the capital of an independent Slovenia. It is all very confusing, at least for the British, especially as Plecnik was trained in Vienna in the office of Otto Wagner, the imperial capital's great city architect. But it was in the new independent Slav states that rose from the ashes of the Hapsburg Empire that this architect's genius fully emerged.

What Mackintosh was to Glasgow, or Gaudi to Barcelona, Plecnik was to Ljubljana, where he designed churches and a great library. Yet some of his finest work was carried out in Prague, where he was first invited to teach after the odious Archduke Franz Ferdinand had stopped him - on racial grounds - succeeding Wagner at the Vienna Academy of Fine Arts.

In Prague, Plecnik designed one of the great modern churches of Europe - the Church of the Sacred Heart in Vinohrady - and transformed the Castle. For Masaryk he designed a series of presidential apartments, complete with an oval lift within a vaulted brick cylinder, and new state rooms, notably an extraordinary columned hall, which acts as an entrance to the Castle. He also transformed the exterior spaces for the benefit of the public. Courtyards were repaved and articulated by new monuments and, above all, he transformed the old ramparts overlooking the city into a paradise garden, enhanced by gazebos, columns, giant urns and pyramids.

This extraordinary, intense Slovene possessed the rare ability to take ancient forms and transform them into something new and different. Unlike Wright and Mackintosh, he cannot be called a pioneer of the modern movement; indeed, he was deeply hostile to Le Corbusier.

But his creative sense of tradition appeals to the post-modern generation, as does the inspired strangeness of much of his work. As the Czech cubist and modernist architect Pavel Janak put it: "In Plecnik's work nothing is ever repeated as it was in the past, but everything is newly conceived, formed and executed. His art still incorporates columns and cornices, but they are designed in a way they never were before..." Anxious that his work should speak to a wide public, Plecnik therefore represents not the narrow exclusivity of the modern movement but a much wider and richer strand of 20th-century architecture which has been ignored until recently.

As an austere and devout Roman Catholic, Plecnik was marginalised in Tito's Yugoslavia and he died, in comparative obscurity, in Ljubljana in 1957. Now he has re-emerged as a great figure. The first article on him in English was published in 1980 by Richard Bassett and in 1983 an exhibition was held at Oxford Polytechnic.

But Plecnik's resurrection really came in 1986 when a major exhibition was held at the Pompidou Centre in Paris. This travelled to several European cities, but not to Prague where, to the Communist authorities, Plecnik's work was an unwelcome reminder that, under Masaryk, Czechoslovakia had been a successful, progressive, democratic state. So the current exhibition in Prague Castle, a joint Czech and Slovenian enterprise called "Josip Plecnik: Architecture of the New Democracy", celebrates both a great architect and the restoration of democracy after the Velvet Revolution.

This is a wonderful exhibition, and an unconventional one. It consists of drawings, photographs, models and furniture (Plecnik's exquisite chairs make Mackintosh's look crude and silly) and examples of his extraordinarily inventive metalwork, exhibited in interiors not normally open to the public. But there is also an exterior promenade. A series of 35 "stops" marked by concrete column-heads on the ground take the visitor from the Matthias Gate to the Bastion Garden, then across the Third Courtyard and down the amazing and clever Bull Staircase to the Rampart Gardens or Garden of Paradise, explaining what Plecnik was doing at each point. As a beautifully designed and intelligent introduction to the mind and achievement of a great architect, this inspiring exhibition is hard to beat. A visit to the "city of Baroque and Gothic" before it finishes on 29 September is greatly recommended.

Plecnik was a product of the 19th century, but he has much to say to the 21st. His work shows how a belief in classicism and in fine craftsmanship need not result in the sterile and pedantic Palladianism of a Quinlan Terry; rather it demonstrates how a rigorous but subtle understanding of the spirit of tradition can produce genuinely creative new work, singing with the resonances and symbolisms which the modern movement rejected. Plecnik also has much to teach us about the creative adaptation of historic buildings, for he showed how new work can fit in with the old while having a distinct modern character of its own. To compare the bold sophistication of what Plecnik achieved in Prague with the current timid and unimaginative restoration of our own Windsor Castle is to see how much our century has lost and forgotten.

'Josip Plecnik: Architecture for the New Democracy' at Prague Castle, Czech Republic, daily until 29 September.