Donald Trump has talked about it, but the Brits are actually doing it.
The UK will start building a four-metre high wall stretching one kilometre through the French port city of Calais to stop migrants jumping on trucks in an attempt to illegally enter Britain.
Work on the huge barrier on a road leading to the port will begin this month and should be completed by the end of the year.
The UK government will pay for the construction under a deal agreed in March that also includes an existing security fence around the entrance to the port and Channel Tunnel.
It comes after truckies staged a protest earlier this week over conditions at the port that have left many fearing for their lives, or subject to violent attacks by migrants desperate to stowaway on trucks bound for the UK.
Drivers have reported having their windscreens smashed with metal bars or being ambushed by burning branches on the road left by men desperate to get them to slow down so they can jump on board.
The situation has become a major flashpoint in the Brexit debate as the Jungle camp on the outskirts of the city has swelled to an estimated 10,000 members following Europe's refugee and migrant crisis.
It's ignited questions over whether France will maintain the 2003 Le Touquet treaty that has allowed British border controls to be located on the French side of the English Channel.
Former President Nicholas Sarkozy, who signed the treaty as interior minister to close a previous camp, Sangatte, and is now hoping for a shot re-election, wants Britain to take back responsibility for its own border post-Brexit. The UK Home Office has dismissed the suggestion.
On Tuesday, UK junior Minister Robert Goodwill told a parliamentary committee the new wall would begin soon.
"We are going to start building this big new wall very soon. We've done the fence, now we are doing a wall," he said.
The estimated $4 million project is one of a spate of new walls to be thrown up around Europe as the continent struggles with an influx of new arrivals.
Norway will build a fence along its arctic border, while Hungary has constructed a fence along the border with Serbia and Austria topped with razor wire. Germany and Austria also closed their borders temporarily last European summer in an attempt to stem the flow of people coming into the country.
Meanwhile Republican presidential hopeful Donald Trump has generated huge headlines and controversy with his plan to build a wall along the US border with Mexico if elected.
Former Mexican President Vincente Fox has slammed the billionaire for the idea and told him to "show some respect" to the Mexican people.
"We don't like him. We don't want him. We reject his message."
"Stop lying! Mexico is not yours to play with, show some respect," he tweeted.
The "Great Wall of Calais" has generated huge reaction in the UK and was trending online Wednesday.
Calais aid worker François Guennoc told The Guardian: "This wall is the latest extension to kilometres of fencing and security surveillance already in place. It will just result in people going further to get round it.
"When you put walls up anywhere in the world, people find ways to go round them. It's a waste of money. It could make it more dangerous for people, it will push up tariffs for people smugglers and people will end up taking more risks."
Earlier this week, French farmers and truckers blocked main routes in and out of the city in protest over the jungle. They claim the extra 2100 police deployed around the port do not make the city safe as they are overstretched and unable to secure the roads.
French Interior Minister Bernard Cazeneuve has said the Jungle will be closed "as quickly as possible", but would be done in a series of stages.