The city hall has turned a blind eye to the spectacular expansion of the Temple of the Holy Family, a gesture of tolerance unlikely to be granted anyone planning a Barcelona loft extension.

But a recent dispute over whether a proposed high-speed train link might undermine the monument's foundations has turned the public spotlight on the unlicensed status of Gaudi's bestknown work.

The council approved Gaudi's plans when he submitted them in 1883, but when he sought approval for a more ambitious project in 1885 the visionary architect never received a reply. Work began, and continues with no completion date in sight, without approval ever having been granted.

Gaudi submitted plans for further extensions in 1916; and in 1990 the Sagrada Familia's building works committee submitted updated paperwork to the then Mayor of Barcelona, Pascual Maragal. Administrative silence remained absolute. This did not deter Gaudi, who continued working on the site until his death in 1924.

"Because this is an exceptional work, it was dealt with through other routes, different from those of normal buildings, " a spokesman for the works told yesterday's El Pais.

A plan was put forward in the '20s for a vast, star-shaped plaza surrounding the building that would give visitors unobstructed views of the undulating steeples and dripping facades. This, too, received no reply. Since then, efforts to complete Gaudi's grandiose project have accelerated.

Fired with enthusiasm, devotees have dusted off Gaudi's plaza project, even though clearing the land today would mean razing houses and shops and evicting 150 families. They have announced an international competition to realise the plan, and even want the town hall to fund the works.

Critics have broken their silence.

"The presumed absence of a correct municipal licence is not just an administrative problem but evidence of lack of town hall control over an important matter, " warned Oriol Bohigas, the architect who transformed Barcelona from a miserable grey city to the stylish beauty it is today.

Neighbours too reached the end of their patience. "Thousands of visitors already invade our neighbourhood and make life unbearable, " a spokesman for the Sagrada Familia Neighbours Association said.

The authorities had indicated their willingness to negotiate with the church's construction committee. But relations have soured badly in recent weeks, after the Gaudi camp protested against a proposed high-speed rail link between Barcelona and the border with France that would tunnel near the building's eye-popping facade. The Catalan regional government and Barcelona city say no other route is viable, but have delayed completion for three years, until 2012. Sagrada Familia's building committee says it'll sue unless the route is shifted.

Civil and religious antagonists who could have struck a deal decades ago are now at daggers drawn.