The 2000-year old House of the Gladiators in the ruins of ancient Pompeii has collapsed.
The house was partially rebuilt after it sustained damage during World World II, and had not been thought at risk of collapse.
It was found in ruins when curators came to open the site to visitors early on Saturday.
Culture Minister Sandro Bondi said some of the frescos on the house's lower walls might have survived.
Antonio Varone, director of excavations at the site, said officials were "trying to preserve the last fragments".
The collapse has raised concerns about whether Italy is spending enough to preserve its archaeological heritage, the BBC reports.
There was speculation that recent heavy rains might have made the structure unstable.
The house, known as the Schola Armaturarum, was used by gladiators for training before fights in the nearby amphitheatre.
Pompeii was destroyed in AD79 when a volcanic eruption from nearby Mount Vesuvius buried the city in ash. Its remains, uncovered in the 18th century, are a world heritage site.