Europe's lessons for Trump's border wall

"Walls always invite challenge."

Since 2015, nearly 1,300 kilometres of border fencing has been built in European countries.

As the debate rages in the U.S. over funding for Donald Trump's proposed wall on the country's southern border, we ask CBC correspondent Nahlah Ayed just how effective Europe's barriers have been in stopping the flow of migrants.

Ayed has travelled across Europe to investigate the recent proliferation of border walls as part of her reporting on the migration crisis.