WATCH: Want to know how the Secret Service protects the new president on Inauguration Day? Nobody knows better than a guy trained to take a bullet.
For the Secret Service, there are miles of ground to cover and one man to protect on Inauguration Day. Former agent Dan Bongino worked Obama's inauguration and presidential detail.
It's all in the preparation
Bongino likens Inauguration Day security to building a house out of Legos. "How do you build a Lego house? The answer is one Lego at a time," Bongino said. "The same way you build a security plan. They’re all big tasks broken down into small digestible chunks."
WATCH: The current special agent in charge of the Washington Field Office explains how Secret Service agents partner up and fan out into zones for Inauguration Day.
So, how does the Secret Service handle the crowds interested in seeing the new commander-in-chief? Pennsylvania Avenue and the parade route are split into one long set of boxes, according to Bongino. And every agent gets a box.
Everything above it, everything below it. This big 4x4 box that goes up and down. You own all of it.
WATCH: President Obama's Inauguration Ceremony
That concept is no different than securing the president at any event. But Bongino says Inauguration Day means there will be more boxes, more bodies, more agencies involved and much more planning. But when it comes to the threat level, Bongino says it's huge no matter who's being sworn in.
"The truth is, the president’s threat level is off the charts. It’s always sky high. You can’t make it 101 percent. It’s 100 percent whether it’s George W. Bush, whether it’s Barack Obama, whether it’s Donald J. Trump. It doesn’t matter," Bongino explained.
So what if Trump decides to flip the script and make a spontaneous jump out of the motorcade somewhere unexpected? Secret Service agents may not like it. But they'll deal.
"You crave order. Order is your friend, for a couple reasons. Order buys you time and time buys you the ability to react," Bongino said.
Still, even a man who would have taken a bullet for the president says agents know they're paid not to boss around the leader of the free world.
I'd tell Trump, be the President. And don't worry about it. We'll figure it out. Always have and they always will.
WATCH: Brian Ebert, current Special Agent in Charge of the Secret Service Washington Field Office, explains their approach at the inauguration