In 1966 during the Vietnam War, Tran Van Lai, a politician, bought a house at 287/70 Nguyen Dinh Chieu Road in District 3 of what was then Saigon.

Over the next few months, he constructed a secret cellar without the knowledge of his family. He used the secret hideaway to store weapons that would be used in the 1968 attack on the Royal Palace. This event was better known as the Tet Offensive.

To avoid suspicion, he put all the dirt collected from digging the bunker into boxes and disposed of them using his car at night. The weapons were also brought in and out in a similar manner, hidden in bamboo cases or rugs. Weapons include TNT, C4 explosives, detonators, rocket launchers, guns, and hand grenades.

Today, the house is a tiny museum and a witness to an important part of Vietnamese history. It was classified as a historical, cultural relic in 1986 by the Ministry of Culture. The coffee shop next door, Cà Phê Đỗ Phủ, also contains secret passages and is owned by Tran Vu Binh, the son of Van Lai.