For months, we heard then candidate Donald Trump make a key promise that would become central to his campaign.

“We’re going to have strong, incredible borders and people are going to come into our country, but they’re going to come in legally. They’re going to come in legally,” Trump said while in a campaign rally in Massachusetts in 2016. “We’re going to build a wall. It’s going to be built.”

Now the prototypes of what might become a new border wall are nearly finished, eight walls by six companies, done in just under 30 days.

FOX’s Jessica Rosenthal takes you inside her tour with a Border Patrol Agent escort and paints the picture of what each border wall prototype looks like and also chats with Deputy Chief Patrol Agent Roy Villarreal as the walls hovered around him about the biggest challenges they are facing currently. Jessica also speaks with residents of Mexico about how they feel about the wall and if Mexico will really pay for it.

Follow Jessica Rosenthal on Twitter: @JessicaFOXNews