Americans have heard it over and over again: Trump is going to build a beautiful wall along the southern border and Mexico is going to pay for it. Yet, most of Trump’s critics view the proposal as pure fantasy. This, as Atlantic staff writer Uri Friedman explains, is a big mistake. Trump’s wall should be taken very seriously. For one, it’s been the centerpiece of his campaign since he announced his candidacy in June of 2015. Secondly, the wall is an encapsulation of Trump’s America-First worldview that provides a glimpse into what his foreign policy might look like in practice.