With a red woollen cap soaking up the baking midday sun and his blue coat covered in dust and drying cement, the wiry, reclusive 81-year-old was in the middle of a self-imposed working day that started at 6am.

"I can't say when it will be finished," he said, surveying the columns, walls, towers, arches and cloisters he has raised above the arid ground of Mejorada del Campo, a small country town near Madrid.

Justo's do-it-yourself cathedral was yesterday a focus of media attention in Spain as news spread that a Spanish ironmonger had donated and delivered the buildings' doors while a French artist was offering to decorate the interior.

It now seems possible that what Justo's own neighbours have often regarded as a useless folly worthy of the legendary Don Quixote may, actually, one day, become the cathedral he pledged to build with his own hands half a century ago.

Visitors wandered in and out of his red-brick and concrete cathedral yesterday, weaving their way past heaps of recycled building materials and mounds of cement bags.

Obsession

Justo ignored them as he pursued the obsession that has kept him busy through searing heat and freezing cold, six days a week, since he was 36.

Journalists were invited to read a written version of why he embarked on his single-minded pursuit.

"Apart from occasional help from others, I have built it all myself," he explains. "I've got up at 3.30 some mornings in order to start work."

The scale of Justo's ambition can be seen in the size of a building whose main temple occupies 1,000 sq metres (10,700 sq ft). The heavy metal frame of a huge cupola is already in place, 35 metres (115ft) up. A dozen 40-metre (130ft) towers are almost complete.

A subterranean crypt, an open-air baptistry, two cloisters, four priests' homes and a sweeping flight of steps up to the soon-to-be-installed front doors are at varying states of completion.

"I am not an architect or a bricklayer, nor do I have any training in building," Justo admits.

The concrete on the larger curved arches was moulded with old tyres. Smaller arches were shaped around car wheels.

Abandoned tin cans and plastic tubes have also been pressed into service.

"There are no plans and no approved, official project," he says. "Everything is in my head."

Materials are recycled, donated, begged off building sites or provided by local brick or tile factories that send him their rejects.

The land itself is a former olive grove that belongs to Justo's family.

The cathedral currently resembles a chaotic cross between a dilapidated medieval monastery and a modern scrap-yard.

Bits of metal poke out here and there from uneven patches of concrete rendering. The deformed bricks on one soaring tower look as though they have been squashed by the weight of what sits on top of them.

Rotting electric cables, rusting scaffolding and bits of old carpet form part of an array of home-made building equipment, along with winches made from rope and old bicycle wheels.

Local sceptics have spent four decades claiming the building is bound to fall in on itself.

"If you don't think it is safe then don't come in," is the reply given by Gregorio Martín, a former missionary who acts as Justo's doorman, to sceptics.

Plenty of visitors do enter, however, attracted by the blossoming popularity not just of the building but of the builder.

A large trestle table with a simple portrait of Pope John Paul II was being used yesterday as a depository for picture cards of saints and virgins, for medallions and for notes of support left by those who already begin to see the stuff of sainthood in Justo.

A group of 20 German priests travel south every July to work alongside him for a few days.

Justo's eccentric dream was born after he was sent home with tuberculosis from a Cistercian monastery almost half a century ago, frustrating his plans for a life of religious contemplation.

"I was inspired by books on cathedrals, castles and other great buildings," he explains. "But my greatest inspiration is Christ."

Ridicule

He has suffered ridicule and the disdain of both the local town hall and Roman Catholic authorities over the decades.

"Now it seems they both want to get involved," mutters Gregorio.

Justo, who lives at his sister's home, has always known people were laughing at him. "As they have seen the cathedral grow, however, they have realised that I am not mad," he told a Spanish newspaper yesterday. "I am not harming anyone."

The German priests say their own prayers here, but the question of whether the cathedral will ever be used for normal worship remains open.

Justo has no building permits. The local bishopric at Alcala de Henares, which will receive the building when he dies, is not sure what to do with it.

In his old age, meanwhile, Justo is becoming a celebrity. He has even starred in a television advertisement for a popular soft drink.

Some see him as an obstinate fool, given over to a pointless, if honourable, endeavour. Even his friends admit that his obsession is out of the ordinary. "You have to be a bit odd to do this," agrees Gregorio.

"People laugh at him," says Ramón Flores, who sells vegetables from a stall across the road. "But he lives off a piece of bread and a tomato a day. I would say he is closer to a saint."

Justo is not bothered by what people think. "I just keep working every day," he says. "I try to be content with what I have done so far."

Two temples

Temple de la Sagrada Familia (Barcelona)

· Work started 1882

· Main architect Antoni Gaudí

· No of towers 12 x 90m-112m high

· Workforce Thousands

· Completion date Unknown

Justo's cathedral

· Work started 1961

· Builder Justo Gallego

· No of towers 12 x 40 metres high

· Workforce One (plus the occasional tourist)

· Completion date Unknown