The so-called Commodus Passage allowed emperors to enter the arena and watch gladiator fights and other spectacles without mixing with crowds.

It was cut through the Colosseum’s foundations between the end of the 1st century AD and the beginning of the 2nd century AD, in addition to the original design.

The Colosseum was inaugurated in 80 AD.

“This passage is now open to the public, it’s the first time. And so (visitors will) appreciate what it was like to be an emperor,” archaeologist Barbara Nazzaro told Reuters.

The corridor was discovered in the 19th century, and linked to Commodus because historical chronicles say he survived an assassination attempt in an underground passage.

“It was very easy to make the connection”, Nazzaro, who oversaw the corridor’s restoration prior to its opening, added.

It once had marble walls, later replaced with plaster decorated with landscapes, the Colosseum Archaeological Park said in a statement.

It also had stuccowork showing mythological scenes on the vault, and representations of arena spectacles, including bear fights and acrobats, in niches at its entrance.

Some traces of the decorations remain, but very damp conditions in the underground passageway have made conservation a struggle.

Nevertheless, visitors will be able to have an idea of what it looked like in antiquity thanks to a virtual reconstruction shown in a video, Nazzaro said.