The air-raid shelter built for Italy's last king two kings Victor Emmanuel III and Umberto II and their families at Villa Ada in Rome has been reopened to visitors after a five-year restoration, Rome Mayor Roberto Gualtieri said Friday.

The bunker was built in May 1943 for the House of Savoy as Allied bombing raids on the Italian capital intensified.

Visitors will also be able to enjoy the villa's extensive grounds and gardens, which have also been restored, Gualtieri said.

Victor Emmanuel III abdicated in favour of Umberto 11, who reigned for 34 days, therefore being dubbed 'the May kKng', before the referendum that turned Italy from a monarchy to a Republic.