There are a handful of Vietnamese men and women, roughly in their early 40s, who share a very unusual distinction: They were born in the Vinh Moc tunnel complex in the Quang Tri region, while their families took shelter from bombs raining down on their village during the Vietnam War.

The tunnel network was created in the Vietnamese Demilitarized Zone in 1965-66, starting at 32 feet (10 meters) underground. The U.S. military believed that the residents of Vinh Moc were supplying food and ammunition to Con Co island, a nearby North Vietnamese military base; to force the villagers to move out, American forces rained up to 500 rockets a day on the region. Instead of fleeing, the villagers went underground.

What began as a few tunnels expanded to a network of around 5,200 feet (1600 meters), with 13 entrances leading from the beach and inland hills. The tunnels were divided into three levels, the deepest at 75 feet (23 meters) deep. Around 400 people from 60 families frequently took refuge there until 1972; their longest continuous stay underground was for 18 months.

Today the tunnels function as a museum. Visitors can see how the two lower levels housed the family quarters. There was a communal kitchen and washrooms, a maternity room, lookout posts, and even an 80-person meeting hall where films were screened, all carved out of hardened clay. One of the key architects of the caves was Le Xuan Vy, whose first son was born in the caves in 1967.

While life and birth went on for months and years underground, the huts and buildings in Vinh Moc were leveled. But the tunnel complex served its purpose—no lives were lost in the subterranean village.