As migrants try to find alternative routes into Europe, governments are looking at how to seal their countrys borders more effectively.\r<br>Fences and walls have been erected at key crossing points around the world. In the US, Republican presidential candidate Donald Trump is calling for a wall to be built along the entire southern border with Mexico. The BBC looked at where the fences are designed to keep out undocumented immigrants.\r<br>Video journalists: Andrew Webb and Olivia Lace-Evans\r<br>\r<br>Subscribe to BBC News HERE \r<br>Check out our website: \r<br>Facebook: \r<br>Twitter: \r<br>Instagram:
