Reuters/Jorge Duenes
Prototypes for U.S. President Donald Trump's border wall with Mexico are seen behind the current border fence in this picture taken from the Mexican side of the border in Tijuana, Mexico, January 27, 2018.
Eight prototypes of President Donald Trump's long-promised border wall stand in San Diego, California, at the Otay Mesa port of entry.
They're made of concrete, steel, and other materials, and designed to withstand even the most persistent breaching tools and intrepid climbers.
Constructions crews spent roughly a month erecting the prototypes, in the first major step the Trump administration has taken toward fulfilling a January executive order to "immediately plan, design and construct a physical wall along the southern border" which the president signed shortly after taking office.
Then, tactical teams took over. Here's what happened: