The project – funded to the tune of €41.8-million from the European Union – started on Wednesday and is seen as crucial for the survival of Pompeii after a series of collapses at the 44-hectare site in the shadow of Mount Vesuvius.
On the eve of the opening ceremony, Italian financial police announced they were investigating Marcello Fiori, a former director of the site appointed by prime minister Silvio Berlusconi in 2009, for alleged abuse of office.
Luigi D'Amora, Pompeii's previous supervisor of restoration work, was also accused of defrauding the state. Meanwhile a former contractor, Annamaria Caccavo, was placed under house arrest for hugely inflating costs.
One contract priced by Caccavo, at €449 882, ended up costing the state €4.84-million, prosecutors said in court documents.
The works "were not essential" for preserving Pompeii and were geared towards holding stage performances in the ruins of the ancient city.
The latest renovations will be managed by a "steering committee" with Italian government ministries and European Union representatives to ensure that the funds are not misspent.
"We will be very strict on the timetable," Fabrizio Barca, Italy's minister for territorial cohesion, who oversees regional spending, said ahead of Wednesday's event which will also include the interior and culture ministers.
European Regional Policy Commissioner Johannes Hahn, who will be the star guest at the ceremony, told Italian news agency ANSA on Tuesday that the project could be a "model" for cultural spending in the European Union.
Mismanagement of Italy's cultural treasures
The erupting volcano devastated Pompeii nearly 2 000 years ago in 79 AD but the ash and rock helped preserve buildings almost in their original state, as well as forming eery shapes around the curled-up corpses of victims of the disaster.
The popular Unesco World Heritage site near Naples has come to symbolise the decades of mismanagement of many of Italy's cultural treasures, as well as the fallout from recent steep cuts in budgets for culture because of austerity measures.
The repairs are aimed at reducing the risk of exposure to the elements, reinforcing the ancient Roman buildings, restoring Pompeii's famous frescoes and increasing video surveillance at the site where security has been lax.
The "Grand Pompeii Project" will also improve facilities for visitors and the European Commission estimates the number of tourists at the site could increase from around 2.3-million a year to 2.6-million by 2017.
Unveiling the plans last year, Prime Minister Mario Monti said it showed the need for "courage and strength" to carry out complex projects in south Italy which has long been plagued by under-investment and high corruption. – AFP