The Trump administration seeks to build a 30-foot-high border wall that is difficult to climb or cut through, according to a pair of contract notices posted to a government website. The notices were ...

A new method offers a quick way to examine its composition. Concrete is the world's most popular building material: we use it to bridge rivers and valleys, build walls and line tunnels. The most ...

Construction is scheduled to begin Tuesday near San Diego on prototypes for a new barrier along the U.S. border with Mexico—the most visible step so far toward President Donald Trump’s long-promised ...