"We're going to build a wall" were practically the first words of Donald Trump's campaign for president.
The plan for a continuous wall on the Mexican border has many friends, and enemies, and practical obstacles.
Ronald Rael is an opponent of the wall, but considers it as both architectural and metaphorical construct.
His book Borderwall as Architecture is a mix of anger, whimsy, and design.
The author, a University of California-Berkeley professor, visits.