The towering 2,000-year-old stone amphitheatre, the biggest in the Roman empire, is Italy’s most popular tourist attraction, drawing 7.6 million visitors in 2019.

But its own beating heart, the underground passages, cages and rooms where prisoners, animals and gladiators waited to pass through trapdoors to enter the arena above their heads – itself long gone – only opened to the paying public today after lengthy renovations.

More than 80 archaeologists, architects and engineers worked on the 15,000 sq metre “hypogeum” for two years to “bring back to the centre of the attention a monument that the whole world loves”, according to Diego della Valle, chairman of Tod’s, the Italian fashion group that funded the work.

The circular balconies, long accessible to tourists, used to accommodate up to 70,000 spectators to watch gladiator fights, executions and animal hunts. Before the hypogeum was built, the arena could also be filled with water to re-enact sea battles.

Now, a new 160m walkway reveals a part of the monument that has not been accessible to visitors.

It is the second part of a three-stage process that started eight years ago, with Tod’s pledging €25 million euros (RM124 million) to pay for the project – one of a number of restorations of Italian landmarks funded by luxury goods firms.

The first phase of the makeover, including a cleanup of the facade, was unveiled in 2016. The final phase involves renewing the galleries and the lighting system, and creating a new visitor centre.

The project is set to be completed in about three years.

Separately, the government will provide the ancient Roman landmark with new hi-tech flooring, which is expected to be in place by 2023.