After excavating more than two meters of earth and reinforced concrete and then jack-hammering through a 278-millimeter ceiling, the hotel opened the hatch on a warren of flooded corridors, chambers and stairways.

In August, the hotel’s general manager, Kai Speth, and his chief engineer dropped through a square meter-wide hole bored into the ceiling, illuminating a subterranean space of nearly 40 square meters.

They found an old wine bottle, a still-intact light bulb, air ducts, graffiti and eerie echoes of a war that ended almost four decades ago and that raged all about this shelter during the so-called Christmas Bombings, the U.S. terror bombing of Hanoi and Haiphong in particular from December 18-30 in 1972.

“In the hotel’s history, we have a story of the American folk singer, Joan Baez, who sought shelter in this bunker during the Christmas Bombings, and who sang some songs beside a Vietnamese guitarist,” said Speth.

“We’ve always known a bunker was here, somewhere in the garden between the pool and the Club Bar, but looking for this wasn’t even on our radar until my chief engineer tried to sink pilings for the new Bamboo Bar.”

The hotel is still unsure on how best to utilize the underground space, but Speth is determined to make something of this novel asset, if only as a museum that shines a light on the methods of Vietnamese resistance during the war.

The Metropole’s standing as a hotel in the middle of a war zone garnered a feature on the cover of Life magazine on April 7, 1967. The magazine featured a row of manholes, about 1.5 meters deep that line a sidewalk outside the hotel. Those manholes did not connect to the hotel’s more spacious shelter but testify to life in a city under siege by U.S. bombers.

Since its inception in 1901, the Sofitel Legend Metropole Hanoi has reigned as the Grande Dame of Vietnamese hospitality and is one of Southeast Asia’s most iconic hotels.

In 2009, the hotel became the first in the Sofitel portfolio to acquire Accor’s Legend brand distinction.