A Pentagon official said Jalalabad is honeycombed with underground fortifications built by the Soviets before their withdrawal from Afghanistan.

A complex network of massive dams and complex semi-secret underground fortifications were built in the present Fidel Castro period.

Jesse took the group step by step through his infiltration of the First Church of the Aryan Universe, and finally, through a complete description of what he had seen in Coldwater's underground fortifications.

The tunnels became a great and complex system of underground fortifications which nowadays criss-crosses the inside of the Rock.

The area occupied by the underground fortifications ... covers about 5 to 6 square kilometers.

According to the same source the construction of the underground fortification was started in 1936.

North Korea responded militarily by digging massive underground fortifications, and forwarded deployment of its conventional forces for a possible attack against the United States stationed in South Korea.

In the underground fortification of Fenomat, usually referred to as the Fenomat Bunker, 6000 people had found refuge but in the course of 8 years this number had increased to 10,000.

Heavy bombing of Taliban military forces and installations continued around the clock, with American bombers and fighters using cluster bombs to attack troop concentrations and other, huge bombs to destroy underground fortifications.

During that time, they lived and worked in their native villages, building an elaborate social-service network and extensive underground fortifications and stashes of modern weaponry that astounded Israel in a month of bitter fighting.