A rock-hewn World War II tunnel linking Castille and the Auberge D’Italie will be open tomorrow for Notte Bianca after being sealed off for almost 60 years.

Built by the British, the maze of tunnels and shelters was intended to offer protection from the Luftwaffe. The tunnel, which will be open for viewing tomorrow and named Shelter 216, starts in the historic vaults of Castille, the Prime Minister’s office, and leads to Auberge D’Italie in Merchants Street.

Architect Edward Said, an expert on the underground spaces in Valletta, explained that it was probably built in 1941 and sealed off in the early 1950s.

The vaults and tunnel will be opened to the public for tomorrow’s annual Notte Bianca event for the third year running – with a new section made accessible every year.

Sealed for almost six decades, workers removed six truckloads of soil and rubble from the blocked-off entrance in Merchants Street.

The thick stone walls are etched with initials of the stone masons who cut through them. Strangely, there are also some swastikas along with sketches, dates and messages. There is still a switch for the Rediffusion radio that used to broadcast the air-raid warnings and sirens with its four-pin socket.

Tiny stalactites cover the ceilings, lamps and pipes while a few stalagmites can be seen on the stone floors – water trickling through the rock, over the years. Mr Said emphasised the importance of not touching these and the debris on the floor as they probably dated back to the war.

The public can visit between 8pm and 1pm. There will be a short talk by Mr Said every 30 minutes. People who suffer from claustrophobia should be careful because of the closed space and slippery stairs.