One of the world's most influential advocates for open borders lives behind a large wall.

Noting that opponents of President Trump have insisted building a wall on the southern border is immoral, the Daily Caller has embarked on an investigative series it calls "Walls Across America."

After traveling to former President Obama's home in Washington, D.C., it went to the mansion owned by billionaire activist George Soros in the Hamptons, east of New York City.

Soros, founder of the Open Society Foundations, donates billions of dollars to far-left causes, including advocates for global open borders.

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"The point of this is not to troll George Soros," said the Daily Caller's Benny Johnson in a video, with Soros' 10-foot wall in the background. "He's a wealthy man. He has a family. He has a wife. He has things he wants to protect.

"He chooses to protect his property with a wall. With security, with cameras, with guards."

See the Daily Caller's visit to the Soros wall:

Protecting the things you love is the same issue for America, he said.

"The way George Soros chooses to," said Johnson, "is with a wall -- and a really big beautiful door where you can ask permission to come inside."

The only thing that is immoral ...

The first segment of the series, featuring Obama's wall, was inspired by a tweet by President Trump on Dec. 30.

"President and Mrs. Obama built/has a ten foot Wall around their D.C. mansion/compound," the president wrote. "I agree, totally necessary for their safety and security. The U.S. needs the same thing, slightly larger version!"

In his Oval Office address last week, Trump noted some "have suggested a barrier is immoral."

"Then why do wealthy politicians build walls, fences and gates around their homes?" he asked.

"They don’t build walls because they hate the people on the outside. But because they love the people on the inside," Trump said. "The only thing that is immoral is the politicians who do nothing and continue to allow more innocent people to be so horribly victimized."

Johnson said in his segment on Obama's wall that he couldn't determine whether or not Trump was right about the height of the wall, because "there are like seven walls preventing me from even finding out."

See the Daily Caller's visit to Obama's wall: