Located 13km to the east of the National Highway 1 and 6km to the north of Cua Tung Beach, Vinh Moc Tunnels (Vinh Thach Commune, Vinh Linh District, Quang Tri Province) considered as the steel fortress which contributed to helping Vinh Moc’s people and forces to against the raids of American and its puppet government in period 1965-1972.

Vinh Moc underground tunnels were dug from 1965 to 1967 with the total length of nearly 2km. They included three layers with the first one was 13m beneath the ground, the second one (15m), and the deepest one (23m). These tunnels were linked with 13 doors (seven to the sea and six to the hills), of which each door functioned as a ventilator.

The tunnels were designed as a miniature underground village where 94 families had lived for many years with necessary equipments including wells, a meeting hall (capacity of 60 people), message boards, maternity hospital, toilets, operation theatre, Hoang Cam stoves, rice warehouses, telephone stations, observation stations, guard posts, and bomb shelters.

Besides Vinh Moc Tunnels, rounding out the top undiscovered wonders on the website’s list are Tatev monastery (Armenia), Taktsang Palphug Monastery (Bhutan), Sultan Omar Ali Saifuddien Mosque (Brunei), Irrawaddy River (Burma), Killing Caves of Phnom Sampeau (Cambodia), Rock Column Forest (China), Kasar Devi/Crank's Ridge (India), Komodo National Park (Indonesia), Yoro Park/Site of Reversible Destiny (Japan), Viengxay Caves (Laos), Mulee Aage Palace (Maldives), Putra Mosque (Malaysia), the Flaming Cliffs (Mongolia), Annapurna Circuit (Nepal), Banaue Rice Terraces (Philippines), Old Airport Road Food Centre (Singapore), Taepyeong Salt Farm (South Korea), Jathika Namal Uyana National Park (Sri Lanka), and Salawin National Park (Thailand).

Pham Thanh