The Emperor Augustus said he found Rome a city of brick - and he left it a city of marble.

But 2,000 years on, the cracks in his legacy are beginning to show.

The Forum, the Colosseum and the palaces of the Palatine Hill still stand as proud testament to the Roman builders' genius. Yet today they are betrayed by monumental neglect.

The problem of course is money.

It costs millions to protect the treasures of Ancient Rome.

Not to mention the funds needed to safeguard the newly discovered ruins, which in Rome they find practically every week. The budget from the Italian Culture Ministry doesn't even begin to cover it.

Honeycomb of cavities

One of the latest closures came in November 2005, when a 16th-Century wall collapsed without warning in a well-visited area, near the Emperor Tiberius' palace.

The collapse prompted officials to investigate the stability of the hill and its monuments.

The Palatine is honeycombed with cavities - the result of centuries of tunnelling and digging.

Instead of demolishing homes and palaces the Romans built on top of them.

So while the structures may look solid from above, below they rest on shaky foundations.

So dangerous have some of the structures become that now less than half of the Palatine Hill is open to the public.

"It is a gigantic challenge to look after Roman monuments," says the British archaeologist Andrew Wallace-Hadrill.

"The Palatine Hill was completely reshaped in antiquity. Part of the hill was cut away and these enormous concrete structures built in its place.

"The great news is that the Romans built far more solidly than we do today - can we think of a modern structure that would survive 2,000 years of abandonment and neglect - but if you allow the land to slide under its feet, it will crack and eventually fall down."

Ravages of weather

One of the big problems is global warming. The climate is changing.

From time to time, the city is deluged with water from freak rainstorms.

Water that seeps into the caverns further erodes the foundations of the hill. Experts say they were considering restoring the ancient Roman sewers to help drain away that rainwater.

The architect in charge of the Colosseum, Piero Meogrossi, tells me he has the technology to study the foundations of the hill and relatively cheap ways of repairing the cracks above.

But he, like everyone else, has limited funding. In fact, Mr Meogrossi tells me he gets just 500,000 euros (£340,000; $646,000) to protect the Colosseum. It is barely enough to pay the running repairs.

This budget is spread thinner as archaeologists continue to dig up more treasure.

New discoveries

Mr Wallace-Hadrill takes me to one of the latest excavations, inside the Roman Forum, led by the Italian archaeologist Andrea Carandini.

"The more you dig, the more problems you create," he says. "But if you want tourists to keep coming, you have to offer them some novelty.

"The fact that Andrea is excavating here is great news. He is digging up the houses of the first kings of Rome. It's fascinating stuff.

"But it's incredibly complicated - and sometimes the only way to protect what you have discovered is to back-fill - to fill it back up with earth again."

There are some things though you just cannot back-fill.

These include the Domus Aurea - Nero's Golden Palace, part of which has recently been restored and reopened to the public.

The ceilings were once covered with gold, ivory and pearls. Its frescoed halls and winding passageways, mostly underground, were preserved thanks to the Emperor Trajan, who buried Nero's megalomania under the foundations of his own sprawling bath complex.

But since the Domus Aurea was opened to the elements, it has become so unstable that only a small section is safe to view.

Fragile structure

We are taken behind the public barriers to areas where groundwater is seeping through the huge vaulted ceilings.

Areas have been closed because the engineers cannot guarantee the structure is stable. So fragile is the structure that many of the rooms are now cocooned in scaffolding.

With money the archaeologists could waterproof from above, but most of the budget they are given is spent trying to protect the mosaic and the frescoes inside.

There are hi-tech probes to measure humidity and the direction of the wind.

But while the experts try to control the moisture inside, the workmen are employed in a constant battle to remove the moss and algae growing over what is left of the gold-covered ceilings.

"In my view," says Mr Wallace-Hadrill, "the government has to find a better way of investing the profits they get from tourism.

"It is a major industry here in Italy, which ripples throughout the economy. They have to find a way of ploughing back the taxes and the profits to preserve this culture.

"It's very difficult for a modern government to convince itself that culture matters. But you don't have to think about it very long to see that it does. It's tourism, stupid. It's the economy!"

In fact tourism accounts for 10% of the national GDP - but with proper investment, say economists, it could be double that.

More than two million people every year tour the Forum and Palatine Hill free of charge. If they paid only a euro each, it would raise crucial extra funds.

In short, Italy faces that classic national dilemma; how to deal today with the heritage of yesterday - in the interests of tomorrow.