Italy's premier Matteo Renzi and shoe magnate Diego Della Valle on Friday attended a ceremony to mark completion of the multi-million euro cleaning of Rome's Colosseum - the first phase of a major project to restore the 2,000-year-old monument.
"Today we are sending an incredible signal to world and giving values that will benefit the entire community," Renzi said.
"It's a joyful day for those of us who believe in achievable projects."
Della Valle, founder of the shoe-and-luxury goods maker Tod's, is paying 25 million euros for the entire project, which began in 2011 during the last government of media tycoon Silvio Berlusconi.
The project's second phase will include restoring the underground passageways, vaults and pits where animals and gladiators waited to be brought into the arena for their gruesome fights to the death.
The Italian state is paying 18 million euros for work to give the Colosseum a floor like it had in ancient times, culture minister Dario Franceschini said at Friday's cermony.
"The work for the arena should be completed within three years (of the allocation of funding) and therefore in 2018," Franceschini said.
The planned floor will enable the Colosseum to become a venue for "very high level cultural events" such as concerts and shows, he said.
The middle of the Colosseum is currently off-limits to visitors as its network of underground tunnels and pits is exposed.
The world-famous monument stayed open throughout its three-year clean-up which used water misters and hand brushes to remove layers of pollution and grime from its northern and southern facades including 31 arches,
During the cleaning process, the current arch enclosure system was replaced with brand-new gates.