The new World Heritage site you can't enter

BRUSSELS, Belgium — The marble-clad palace, crowned with a quartet of muscular copper nudes, is a familiar landmark for thousands of Brussels' commuters who drive past every evening on their way to the leafy eastern suburbs.

But the treasure-packed interior of the Stoclet Palace is a mystery to all but a privileged handful and the unique artworks it contains are more remote to inhabitants of the Belgian capital than the Taj Mahal or Pyramids of Giza.

Last year, the Stoclet Palace joined the United Nations’ list of the world’s greatest heritage sites. It was one of just four European monuments added to the list, a reflection of the palace’s importance to the history of modern art, architecture and design.

The masterpiece, generally considered one of the finest private houses built in the 20th century, remains in private hands. Although the state is financing repairs and maintenance, the palace remains strictly off limits to the public.

“Very few people have ever visited it and there are hardly any photographs. That’s crazy when you think the Belgian taxpayer is paying for its repairs,” said local councilor Gauthier van Outryve d’Ydewalle.

Brussels banker Adolphe Stoclet ordered the palace built in 1901 on the designs of the Austrian architect Josef Hoffmann, founder of the Wiener Werkstatte movement, which was revolutionizing art and design in Vienna.

The palace is the movement’s masterwork. Hoffmann broke with the ornate art nouveau style then fashionable in the Belgian capital, creating a grand home with clean, rectangular lines that would deeply influence the modernist and art deco movements in the decades that followed.

The Viennese movement aimed to move beyond mere architecture to create complete works of art in which the furniture, lighting, garden, floor tiles, carpets and all other elements of decoration were designed down by to the last detail to produce a unified whole.

To cap it all, Hoffman invited the great Viennese painter Gustav Klimt to create a monumental frieze — "The Tree of Life" — a mosaic encrusted with gold and precious stones that covers the dining room walls. There are also sculptures and paintings by other leading artists of the time.

“The interest of the house is acknowledged all over the world,” said the citation from the U.N.’s cultural agency UNESCO including the building on the world heritage list.

“It is a remarkable illustration of the birth of constructive and decorative modernity, and is frequently presented as an example in schools of architecture all over the world.”

After its completion in 1911, the palace played host to glamorous parties for the cultural glitterati of the time. Guests included Igor Stravinsky, Jean Cocteau and Claude Debussy.

In recent times, however, the palace has fallen on hard times. It has lain empty for years, apart from the live-in caretakers, while the descendents of Aldolphe Stoclet squabble over the property’s future. Estimates have put the value of the house at at least 100 million euros ($137 million), but they may be conservative, given the fact that a single painting by Klimt sold for $137.5 million in 2006.

Ownership of the house and contents is shared among seven Stoclet heirs. The Belgian government recently won a legal battle to prevent some of the heirs from selling off pieces of furniture, but while the house and its contents are now protected, there is no clear idea as to what will happen to the property.

Some of the owners have indicated they would agree to a limited opening to the public, others are firmly opposed, claiming hordes of visitors would ruin the building.

“It’s up to the owners to decide what to do with the property and they have the right to keep it completely private if they wish. There is no obligation linked to the UNESCO decision to open it to the public,” said Pascale Ingelaere, a senior adviser on heritage issues to the president of Brussels’ regional government.

The regional government is hoping, however, to open exploratory talks with the family on the building's future in the next few months, she said.

“We would like to discuss this with the owners, to see to what extent we could envisage in the short- or medium-term an eventual opening to the public,” Ingelaere said.

In the meantime, the regional government is paying almost half the costs of a 1.3 million euro ($1.8 million) program to carry out the most urgent preservation work up to 2014.

For the immediate future, though, there is little chance the authorities would be able to find the millions of euros needed to buy the property, even if the family could be persuaded to sell the property.

“Just now, we have some rather serious budget problems, so it’s not really the right moment,” Ingelaere acknowledged. “However, if ever we had a really serious threat to the building, we’d get around the table and find a solution. We won’t let the Stoclet Palace fall down.”

That at least is a sign of progress in a city that has a bad reputation for protecting its architectural heritage.

While four turn-of-the-century homes built by the city’s own art nouveau genius Victor Horta have been included on the UNESCO World Heritage list since 2000, his masterpiece — the House of the People — was demolished in 1965 and replaced by a non-descript office block.