Ho Chi Minh City (CNN) — Most people who travel to Ho Chi Minh City will make the hour or so drive out of town to visit the Cu Chi tunnels, used by the Viet Cong during the Vietnam War.

What most won't realize is that right under their feet in the city itself is a subterranean network, smaller but no less remarkable than the claustrophobic tunnels that housed so many Vietnamese fighters during the war.

Down a nondescript alleyway in District 10 is a former family home that, during the mid-1950s, was known as Secret Cellar B. The family that lived there was charged by the revolutionary Vietnamese forces with housing a printing press to produce Vietnamese propaganda posters . To avoid raids, there was only one place to put it: underground.

In one of the sparsely furnished rooms, preserved as they were more than 60 years ago, sits an old teak wardrobe. Open the door, and it offers the entrance to an alternative world, as pivotal to anti-colonial Vietnamese back then as Narnia was to the children of C.S. Lewis' novels.

Tight fit

Visitors to Vietnam can step into the wardrobe and climb down through a hole, around shoulder width, and into the cellar. The tunnel leading to it was excavated to be only as wide as necessary, so the crawl or bum-shuffle through the twisting dimly lit passage remains an uncomfortable experience.

"In 1951 the French and their allies had complete control of the south (of Vietnam), so all the real revolutionary activity would be happening in the north," says Tim Doling , who conducts heritage tours in Ho Chi Minh City.

"They would have a transistor radio (in the tunnels) and they'd be transcribing news of what would be happening in the north. It was to encourage the local people to support the revolutionary movement. "

To ventilate the tiny space, another tunnel was dug leading up to a well, creating a flow of air for those stationed inside.

Excavated between February and May 1952, Secret Cellar B was in operation until 1957 when it was decommissioned because of security concerns and then filled with soil in 1959 to avoid detection. "It's not quite on the tourist trail, yet," says Doling. "But it is a very special place."

More to explore

Today, visitors can access the tunnels only through an appointment made with District 10 Office for Culture, Sports and Tourism.

Elsewhere in the city are other cellars and hidden rooms that played important roles in the efforts by communist Vietnamese to reunify the country, especially as the conflict intensified in the 1960s. Each has a story of ingenuity and bravery behind its creation and operation.

A printing press in the cellar of a house on Gia Phu in District 6 was dug and operated under the cover of clanking machines producing locks for school bags and remained undetected until 1970.

Other cellars were constructed either as munitions dumps (stuffed with arms often moved into the city from rural Cu Chi) or as places to hide revolutionary activists. Some of the locations were downright brazen, such as the house at 91 Pham Van Chi, opposite the District 6 police station and courtroom.

Tunnels under the Independence Palace and Ho Chi Minh Museum, both built on the order of a twitchy South Vietnam president Ngo Dinh Diem can be visited by tourists. But even in these well-known warrens of intrigue, Doling believes that there is more to discover, like a fabled connecting tunnel between the two.

"Ho Chi Minh is a fascinating place and everywhere you look are little nooks and crannies," he says.

"I've always felt that the city is seen as an economic hub where visitors only stay for one or two nights.

"What tourist groups here offer is quite limited so I've be concentrating on trying to research the history to expand the resources for tourism."